With this command:

gsettings reset-recursively org.cinnamon

After I used the command the window list applet stopped working but a reboot fixed it

Problem has been solved. thanks for your help.

The command did it!!! Even stremio looks fine. Those icons still behave strangely, they ignore the icon size option in “panel settings” and they have a bit more padding than the rest but I think that was their “normal” behaviour like you said in your other comment.
Thank you very much, my hero, those kinds of errors annoy me more than they should. Gonna save this command in my “usefull commands for dummies” file.

Nope :c I tested all the parameters mentioned in the thread and none worked. Thanks tho.