This protocol lets Wayland client to ask the compositor to draw the cursor rather than the Wayland client drawing the cursor itself.
Seems like Mutter merged this support a week ago: https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3668
Does this mean we will no longer have the cursor changing when we hover on certain flatpak apps?
No, apps are free to use client side cursor decorations if they want to. Games typically do for their custom cursors. Gnome may want to do this, I don’t know.
Also, this protocol is currently only supported in GTK4. Wayland clients using GTK3 don’t have access to it. Chromium uses GTK3 but they added support for it outside of GTK. I don’t think Firefox supports it.
The giant cursor will keep tormenting me for the foreseeable future.