[gtirloni]

Try flatseal and see if you can tweak the permissions.

Re: terrible look, I face the same thing with Telegram (the mouse reverts to whatever is the default in Qt and ignores the system settings). I haven't been able to fix that.

[shaicoleman]

This is what fixed the cursor for me (Linux Mint Cinnamon, HiDPI):

  sudo flatpak override --env XCURSOR_THEME=DMZ-White
  mkdir -p ~/.icons/default/cursors/
  cp -R /usr/share/icons/DMZ-White/cursors/. ~/.icons/default/cursors/