Thank you. I tested this on my system because Chromium is installed here, while Google Chrome is not.
I started Chromium several times, opened multiple websites, closed it, started it again and repeated the test.
The problematic fontconfig symlinks were not recreated. I then performed another full reboot of the computer.
After reboot, Portmaster started normally, WebKitWebProcess is running at about 0.03% CPU, no logical CPU core is stuck at 100%, and another check of ~/.cache/fontconfig still showed no symbolic links.
So at least with the Chromium version installed on my Zorin OS 18.1 system, simply starting and using Chromium does not reproduce the problem or recreate the problematic cache symlinks.
I agree, however, that the links could potentially be recreated later by whichever application originally created them. I still have not identified that application.