I agree with your findings.
The “fromIccProfile” message is just informational.
The Brief
When installed via pacman spyder consumes 100% of a cpu and is unresponsive. spyder is 5.4.1.
I uninstalled via pacman and reinstalled via pip and spyder worked. spyder is 5.4.2.
Details
I know of spyder, but don’t use it. I brought up a current XFCE VM and installed spyder 5.4.1 via pacman.When I ran spyder from the command line, it failed because it requires python-appdirs, which I see you installed
Probably should be a package dependency 
I started spyder from the command line again, and observed:
- used 100% of a cpu (
htop
)
- window moves, but menu and all other controls unresponsive
- when closed via the window title bar close button, a dialog box is displayed with the message, “This window might be busy and is not responding”.
I reviewed the following:
There is a 5.4.2 release, dated Jan 18. I thought I’d try it and see how things went. Perhaps should be marked outdated at arch 
pacman
To install a package, the command is: pacman -S spyder
as root. Note: if you ever use pamac, the install is executed using your normal user id because it is handled via pamac, specifically policy-kit.
The package metadata is stored in the local repositories (/var/lib/pacman/sync/). If the package is not in cache (/var/cache/pacman/pkg/) , pacman will download from a mirror to cache and install. The option "-y"
will update the local repositories if it is out of date, a double "-yy"
will always update the local repositories. The "-u"
will update your system.
To make sure your mirrors are okay, use pacman-mirrors. The state of mirrors can also be viewed at https://repo.manjaro.org/.
pacman-mirrors # status
pacman-mirrors --list # list country codes
pacman-mirrors -c COUNTRY # creates a custom mirror list (/var/lib/pacman-mirrors/custom-mirrors.json).
pacman-mirrors -f # orders custom mirror list or if none, default pool (which is all) into /etc/pacman.d/mirrorlist.
Always scan the Stable Update Announcements before doing an update — at least the first 2 entries. You can follow it via RSS or this forum > Profile > Preferences > >Notifications > Categories. If you use the later, a number will appear over your Profile Image when there is something new.
Install from pip (proof of concept)
I followed a combination of
sudo pacman -S python-pip
# ▼▼▼ as regular user ▼▼▼
mkdir -p src/Projects
cd src/Projects
python -m venv mySpyder
find -newermt '1 minute ago'
source mySpyder/bin/activate
pip install spyder numpy scipy pandas matplotlib sympy cython
spyder
deactivate
Please see my update below. A pacman install can be successful. It is a theming problem with kvantum and QT styles. Who knew 