I've been getting some odd issues with my Quest 2 since upgrading to V.28, not limited to but including the following:
1. Graphical Artifacts - in games. So far I've noticed this in Vader Ep 2 and 3 but there might be more. It looks like tiny white stuck pixels (a few dozen or so) for a few seconds and then they disappear? I think that it's mainly the left side lens.
2. Audio glitches - Same games as above (so far) but sometimes the glitches are audio based, such as the odd character sounding as though they are under water...like Merman from He-Man in the 1980s!
3. Random Lock-ups - usually when looking / interacting with the main menu or when using apps like youtube, the screen freezes and you can look around into the nothingness around it. It's quite freaky and can only be likened to a VR experience of a scene from the film "Get Out"! This has only cleared itself once and usually requires a reboot
4. Loss of Guardian - which has coincided with item 3 above on one occasion. Sometimes this just comes back and other times you have to reboot to get it to work.
I've tried switching off all experimental modes...nothing seems to make any difference. The device has had no drops etc, it's just played up since V.28