I use a Mac and never had this problem, so it's hard for me to just guess what the problem is. Since it started prior to Catalina, I would personally (not suggesting you do this) roll back the OS and see if the problem is still present, before the ability to do so is lost. Do you run any checkers on your Mac? I use CleanMyMac and Gemini to keep my system clean and free up space. It also scans for corrupted files, etc. You could pull up terminal to fire up GIMP and see what the system says.
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"In order to attain the impossible, one must attempt the absurd."
~ Miguel de Cervantes