Comment 12 for bug 1304067

May have found a possible fix you guys can try. I had a similar problem on Deepin OS, where the mouse cursor changed size depending on what application you hovered over, and sometimes it would just be big no matter what. First make sure that your cursor is set using the --config x-cursor-theme method above, then

Edit "/etc/X11/Xresources/x11-common" with nano and add "Xcursor.size: 24". Or add whatever size you want instead of 24. Then reboot. This MAY fix the problem if you're willing to give it a try. I can't test it as I'm running a Ryzen system and it doesn't play nice with older kernels.

Hope this helps! Good luck!