Some applications show ugly mouse pointer after Debian 11 > 12 update

Hi there. I've got two types of applications after updating Debian from 11 to 12, and consequently moving from Gnome 3 to Gnome 4. Those that seem fine and show the expected mouse point (system, Firefox, Thunderbird, LibreOffice etc.):

nice-cursor

and others that now show a very ugly "fat penguin" kind of cursor, which also moves quite sluggishly (Mixxx, FreeCAD, OpenSCAD):

ugly-cursor

I looked threw "Tweaks" but didn't notice any particular setting that might affect this. Any idea how I can make those applications use a descent mouse cursor?