I don't know why I can't see imgurs images... so I'm not sure if your issue is the same that I encountered but give it a try :
When you install cursors, they are in your home folder /home/user/.icons or /home/user/.local/icons, etc
That tends to make that your desktop end file manager get the "good" cursors when other apps (particularly flatpaks and snaps) don't get the right cursors.
The fix is to install the cursors to /usr/