This is caused by absence of a functional DNS on the system in question - possibly because your VPN provided DNS is in your resolv.conf and your VPN connection is not starting as expected.
You can verify the content using
cat /etc/resolv.conf
No Manjaro is not breaking your system. Without knowing which VPN provider you use - it is purely guessing.
Not many vpn providers - surfshark as an exception - provides installation instrucitons for Arch based distributions.
When you sync your system - any custom AUR package may break as a result of the system being updated.
The rule of thumb is - rebuild your custom package(s) when you have synced your system.