@spikeyxxx – I wasn’t able to recreate the issue in 3.2 using just a simple cube.
I went ahead and created 2 bugs using just Pot Head’s torso.
T98998: Faces Hidden in Edit Mode May be Painted in Texture Paint.
T98996: Texture Paint Mask Not Visibly Updating in Viewport.
They may end up being the same issue, but in case they aren’t I reported them separately. We’ll see what the Blender Team says.