May be there is one point missing:
Because i often can´t access AUR with my orginal IP, i am using a VPN (Proton) when doing updates. So, i removed shiny-mirrors, and did a reinstall with pacman
On one pc there is no problem.
sudo shiny-mirrors refresh -L 10 -M Transfer
sudo: shiny-mirrors: Befehl nicht gefunden
sudo pacman-mirrors -f 9
::INFO Lade Mirrorliste herunter von Manjaro
::INFO => Mirror pool: https://repo.manjaro.org/mirrors.json
::INFO => Mirror status: https://repo.manjaro.org/status.json
::INFO Nutze Standard-Mirrordatei
::INFO Frage Mirrors ab - Dies kann einige Zeit in Anspruch nehmen
0.747 United_States : https://coresite.mm.fcix.net/manjaro/
0.701 Iran : https://mirror.mobinhost.com/manjaro/
0.254 France : https://mirrors.eric.ovh/manjaro/
0.681 United_States : https://cofractal-ewr.mm.fcix.net/manjaro/
0.212 Netherlands : https://manjaro.mirrors.lavatech.top/
1.001 Sweden : https://ftpmirror1.infania.net/mirror/manjaro/
0.878 United_States : https://southfront.mm.fcix.net/manjaro/
0.193 Germany : http://ftp.uni-kl.de/pub/linux/manjaro/
3.915 China : https://mirrors.sjtug.sjtu.edu.cn/manjaro/
::INFO Schreibe Mirrorliste
::Germany : http://ftp.uni-kl.de/pub/linux/manjaro/stable
::Netherlands : https://manjaro.mirrors.lavatech.top/stable
::France : https://mirrors.eric.ovh/manjaro/stable
::United_States : https://cofractal-ewr.mm.fcix.net/manjaro/stable
::Iran : https://mirror.mobinhost.com/manjaro/stable
::United_States : https://coresite.mm.fcix.net/manjaro/stable
::United_States : https://southfront.mm.fcix.net/manjaro/stable
::Sweden : https://ftpmirror1.infania.net/mirror/manjaro/stable
::China : https://mirrors.sjtug.sjtu.edu.cn/manjaro/stable
::INFO Mirrorliste erzeugt und gespeichert nach: /etc/pacman.d/mirrorlist
sudo pacman -Ss shiny-mirrors
extra/shiny-mirrors r269.0e59fd0-2
An alternative to Manjaro's pacman-mirrors, rewritten in Rust! A tool to find the best mirrors for you!
sudo pacman -S shiny-mirrors
Abhängigkeiten werden aufgelöst …
Nach in Konflikt stehenden Paketen wird gesucht …
Pakete (1) shiny-mirrors-r269.0e59fd0-2
Gesamtgröße des Downloads: 1,79 MiB
Gesamtgröße der installierten Pakete: 5,00 MiB
:: Installation fortsetzen? [J/n]
:: Pakete werden empfangen …
shiny-mirrors-r269.0e59fd0-2-x86_64 1837,1 KiB 3,21 MiB/s 00:01 [---------------------------------------------------------------------] 100%
(1/1) Schlüssel im Schlüsselbund werden geprüft [---------------------------------------------------------------------] 100%
(1/1) Paket-Integrität wird überprüft [---------------------------------------------------------------------] 100%
(1/1) Paket-Dateien werden geladen [---------------------------------------------------------------------] 100%
(1/1) Auf Dateikonflikte wird geprüft [---------------------------------------------------------------------] 100%
(1/1) Verfügbarer Festplattenspeicher wird ermittelt [---------------------------------------------------------------------] 100%
:: Pre-transaction-Hooks werden gestartet …
(1/1) Performing snapper pre snapshots for the following configurations...
==> root: 751
:: Paketänderungen werden verarbeitet …
(1/1) Installiert wird shiny-mirrors [---------------------------------------------------------------------] 100%
:: Post-transaction-Hooks werden gestartet …
(1/3) Reloading system manager configuration...
(2/3) Arming ConditionNeedsUpdate...
(3/3) Performing snapper post snapshots for the following configurations...
==> root: 752
sudo pacman -Ss shiny-mirrors
extra/shiny-mirrors r269.0e59fd0-2 [Installiert]
An alternative to Manjaro's pacman-mirrors, rewritten in Rust! A tool to find the best mirrors for you!
sudo shiny-mirrors refresh -L 10 -M Transfer
No continent or country set, using a geolocation based on your public IP Address endpoint.
41ms Global : https://mirrors.manjaro.org/repo/
41ms Global : https://mirrors2.manjaro.org/
68ms Germany : https://mirror.alpix.eu/manjaro/
56ms Germany : https://ftp.gwdg.de/pub/linux/manjaro/
26ms Germany : https://manjaro.kurdy.org/
75ms Germany : https://ftp.rz.tu-bs.de/pub/mirror/manjaro.org/repos/
95ms Germany : https://ftp.tu-chemnitz.de/pub/linux/manjaro/
100ms Germany : http://ftp.uni-kl.de/pub/linux/manjaro/
53ms Germany : https://mirror.23m.com/manjaro/
55ms Germany : https://ftp.halifax.rwth-aachen.de/manjaro/
The average Mirror Time was 61ms
sudo shiny-mirrors refresh -L 10 -M Transfer
No continent or country set, using a geolocation based on your public IP Address endpoint.
63ms Global : https://mirrors.manjaro.org/repo/
61ms Global : https://mirrors2.manjaro.org/
81ms Global : https://mirrors.cicku.me/manjaro/
81ms Switzerland : https://mirror.init7.net/manjaro/
The average Mirror Time was 72ms

On the other PC, there is no problem while the VPN is off
sudo pacman -Ss shiny-mirrors
[sudo] Passwort für andreas:
extra/shiny-mirrors r269.0e59fd0-2 [Installiert]
An alternative to Manjaro's pacman-mirrors, rewritten in Rust! A tool to find the best mirrors for you!
sudo pacman -R shiny-mirrors
Abhängigkeiten werden geprüft …
Pakete (1) shiny-mirrors-r269.0e59fd0-2
Gesamtgröße der entfernten Pakete: 5,00 MiB
:: Möchten Sie diese Pakete entfernen? [J/n]
:: Pre-transaction-Hooks werden gestartet …
(1/1) Performing snapper pre snapshots for the following configurations...
==> root: 8783
:: Paketänderungen werden verarbeitet …
(1/1) Entfernung läuft shiny-mirrors [---------------------------------------------------------------------] 100%
Warnung: /etc/shiny-mirrors.conf wurde als /etc/shiny-mirrors.conf.pacsave gespeichert
:: Post-transaction-Hooks werden gestartet …
(1/3) Reloading system manager configuration...
(2/3) Arming ConditionNeedsUpdate...
(3/3) Performing snapper post snapshots for the following configurations...
==> root: 8784
(removed packages from /var/cache/pacman)
sudo pacman -Ss shiny-mirrors
extra/shiny-mirrors r269.0e59fd0-2
An alternative to Manjaro's pacman-mirrors, rewritten in Rust! A tool to find the best mirrors for you!
sudo pacman-mirrors -f 9
::INFO Lade Mirrorliste herunter von Manjaro
::INFO => Mirror pool: https://repo.manjaro.org/mirrors.json
::INFO => Mirror status: https://repo.manjaro.org/status.json
::INFO Nutze Standard-Mirrordatei
::INFO Frage Mirrors ab - Dies kann einige Zeit in Anspruch nehmen
0.642 Iran : https://mirror.mobinhost.com/manjaro/
2.355 Australia : https://mirror.aarnet.edu.au/pub/manjaro/
0.414 Denmark : https://mirrors.dotsrc.org/manjaro/
0.348 Spain : https://mirror.raiolanetworks.com/manjaro/
0.962 United_States : https://coresite.mm.fcix.net/manjaro/
0.341 United_Kingdom : https://www.mirrorservice.org/sites/repo.manjaro.org/repos/
0.592 Spain : https://ftp.caliu.cat/pub/distribucions/manjaro/
0.715 United_States : https://forksystems.mm.fcix.net/manjaro/
1.307 United_States : https://codingflyboy.mm.fcix.net/manjaro/
::INFO Schreibe Mirrorliste
::United_Kingdom : https://www.mirrorservice.org/sites/repo.manjaro.org/repos/stable
::Spain : https://mirror.raiolanetworks.com/manjaro/stable
::Denmark : https://mirrors.dotsrc.org/manjaro/stable
::Spain : https://ftp.caliu.cat/pub/distribucions/manjaro/stable
::Iran : https://mirror.mobinhost.com/manjaro/stable
::United_States : https://forksystems.mm.fcix.net/manjaro/stable
::United_States : https://coresite.mm.fcix.net/manjaro/stable
::United_States : https://codingflyboy.mm.fcix.net/manjaro/stable
::Australia : https://mirror.aarnet.edu.au/pub/manjaro/stable
::INFO Mirrorliste erzeugt und gespeichert nach: /etc/pacman.d/mirrorlist
sudo pacman -S shiny-mirrors
Abhängigkeiten werden aufgelöst …
Nach in Konflikt stehenden Paketen wird gesucht …
Pakete (1) shiny-mirrors-r269.0e59fd0-2
Gesamtgröße des Downloads: 1,79 MiB
Gesamtgröße der installierten Pakete: 5,00 MiB
:: Installation fortsetzen? [J/n]
:: Pakete werden empfangen …
shiny-mirrors-r269.0e59fd0-2-x86_64 1837,1 KiB 2,23 MiB/s 00:01 [---------------------------------------------------------------------] 100%
(1/1) Schlüssel im Schlüsselbund werden geprüft [---------------------------------------------------------------------] 100%
(1/1) Paket-Integrität wird überprüft [---------------------------------------------------------------------] 100%
(1/1) Paket-Dateien werden geladen [---------------------------------------------------------------------] 100%
(1/1) Auf Dateikonflikte wird geprüft [---------------------------------------------------------------------] 100%
(1/1) Verfügbarer Festplattenspeicher wird ermittelt [---------------------------------------------------------------------] 100%
:: Pre-transaction-Hooks werden gestartet …
(1/1) Performing snapper pre snapshots for the following configurations...
==> root: 8785
:: Paketänderungen werden verarbeitet …
(1/1) Installiert wird shiny-mirrors [---------------------------------------------------------------------] 100%
:: Post-transaction-Hooks werden gestartet …
(1/3) Reloading system manager configuration...
(2/3) Arming ConditionNeedsUpdate...
(3/3) Performing snapper post snapshots for the following configurations...
==> root: 8786
sudo pacman -Ss shiny-mirrors
extra/shiny-mirrors r269.0e59fd0-2 [Installiert]
An alternative to Manjaro's pacman-mirrors, rewritten in Rust! A tool to find the best mirrors for you!
sudo shiny-mirrors refresh -L 10 -M Transfer
No continent or country set, using a geolocation based on your public IP Address endpoint.
43ms Global : https://mirrors.manjaro.org/repo/
53ms Global : https://mirrors2.manjaro.org/
82ms Germany : https://ftp.rz.tu-bs.de/pub/mirror/manjaro.org/repos/
82ms Germany : https://mirror.alpix.eu/manjaro/
59ms Germany : https://ftp.gwdg.de/pub/linux/manjaro/
48ms Germany : https://manjaro.kurdy.org/
125ms Germany : https://ftp.tu-chemnitz.de/pub/linux/manjaro/
97ms Germany : http://ftp.uni-kl.de/pub/linux/manjaro/
59ms Germany : https://mirror.23m.com/manjaro/
67ms Germany : https://ftp.halifax.rwth-aachen.de/manjaro/
The average Mirror Time was 71ms

But there is a problem while VPN is connected !
VPN on
sudo shiny-mirrors refresh -L 10 -M Transfer
No continent or country set, using a geolocation based on your public IP Address endpoint.
73ms Global : https://mirrors.manjaro.org/repo/
97ms Global : https://mirrors2.manjaro.org/
89ms Global : https://mirrors.cicku.me/manjaro/
87ms Unknown : https://mirror.it4i.cz/manjaro/
103ms Unknown : https://mirror.dkm.cz/manjaro/
The average Mirror Time was 90ms
thread 'main' panicked at shinylib/src/geo.rs:600:18:
If this happened please report this on the git repo! (get_continent)
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
[1] 8218 IOT instruction sudo shiny-mirrors refresh -L 10 -M Transfer
sudo pacman-mirrors -f 9
::INFO Lade Mirrorliste herunter von Manjaro
::INFO => Mirror pool: https://repo.manjaro.org/mirrors.json
::INFO => Mirror status: https://repo.manjaro.org/status.json
::INFO Nutze Standard-Mirrordatei
::INFO Frage Mirrors ab - Dies kann einige Zeit in Anspruch nehmen
1.940 Bangladesh : https://mirror.xeonbd.com/manjaro/
0.262 Austria : https://mirror.easyname.at/manjaro/
0.272 Netherlands : https://mirror.koddos.net/manjaro/
0.665 Italy : https://ct.mirror.garr.it/mirrors/manjaro/
0.186 Germany : https://ftp.halifax.rwth-aachen.de/manjaro/
1.334 Colombia : https://edgeuno-bog2.mm.fcix.net/manjaro/
1.959 United_States : https://mirrors.ocf.berkeley.edu/manjaro/
2.087 Singapore : https://mirror.freedif.org/Manjaro/
2.425 Vietnam : https://mirror.meowsmp.net/manjaro/
::INFO Schreibe Mirrorliste
::Germany : https://ftp.halifax.rwth-aachen.de/manjaro/stable
::Austria : https://mirror.easyname.at/manjaro/stable
::Netherlands : https://mirror.koddos.net/manjaro/stable
::Italy : https://ct.mirror.garr.it/mirrors/manjaro/stable
::Colombia : https://edgeuno-bog2.mm.fcix.net/manjaro/stable
::Bangladesh : https://mirror.xeonbd.com/manjaro/stable
::United_States : https://mirrors.ocf.berkeley.edu/manjaro/stable
::Singapore : https://mirror.freedif.org/Manjaro/stable
::Vietnam : https://mirror.meowsmp.net/manjaro/stable
::INFO Mirrorliste erzeugt und gespeichert nach: /etc/pacman.d/mirrorlist
VPN off
sudo shiny-mirrors refresh -L 10 -M Transfer
No continent or country set, using a geolocation based on your public IP Address endpoint.
53ms Global : https://mirrors.manjaro.org/repo/
47ms Global : https://mirrors2.manjaro.org/
95ms Germany : https://ftp.rz.tu-bs.de/pub/mirror/manjaro.org/repos/
93ms Germany : https://mirror.alpix.eu/manjaro/
60ms Germany : https://ftp.gwdg.de/pub/linux/manjaro/
44ms Germany : https://manjaro.kurdy.org/
141ms Germany : https://ftp.tu-chemnitz.de/pub/linux/manjaro/
108ms Germany : http://ftp.uni-kl.de/pub/linux/manjaro/
78ms Germany : https://mirror.23m.com/manjaro/
67ms Germany : https://ftp.halifax.rwth-aachen.de/manjaro/
The average Mirror Time was 78ms
VPN off
sudo shiny-mirrors refresh -L 10 -M Transfer
No continent or country set, using a geolocation based on your public IP Address endpoint.
55ms Global : https://mirrors.manjaro.org/repo/
46ms Global : https://mirrors2.manjaro.org/
95ms Germany : https://ftp.rz.tu-bs.de/pub/mirror/manjaro.org/repos/
91ms Germany : https://mirror.alpix.eu/manjaro/
61ms Germany : https://ftp.gwdg.de/pub/linux/manjaro/
44ms Germany : https://manjaro.kurdy.org/
140ms Germany : https://ftp.tu-chemnitz.de/pub/linux/manjaro/
84ms Germany : http://ftp.uni-kl.de/pub/linux/manjaro/
56ms Germany : https://mirror.23m.com/manjaro/
68ms Germany : https://ftp.halifax.rwth-aachen.de/manjaro/
The average Mirror Time was 74ms
At first, I thought this only happened after several attempts.
My theory (but not yet verified):
The problem only occurs when the VPN is connected to a specific country.
Possibly, if the starting point on the internet has a certain range of IP addresses that GeoIP cannot resolve (cleanly). (At least that’s how I understand the error message.)
The VPN’s destination country is selected randomly (unless I choose it manually). This explains why I had problems on one PC but not on the other.