Transient glitches/flashes when editing Photos since Big Sur

Sorry, rebooting the Mac etc. is normally useless (altough it seems to have helped you). I see the glitches, too. It is a bug in Photos or Metal, I believe. This bug typically occurs when the app uses multiple threads and/or graphics buffers. The synchronisation is just not done properly between the threads and/or graphics buffers.

As long as these are only glitches we should be happy and hope that this is going to be solved in an update.

hi

I've used Photos for the first time since updating to Big Sur and I too get these glitches. it only happened 2/3 times and then stopped. it normally did it when I was adjusting brightness on one photo, but not on subsequent photos.

I expect it'll be resolved in an update.

Greg

Hi Everybodyknows,

Thanks for using Apple Support Communities! We see you're having an issue with your iMac and are concerned there may be a hardware issue.

If you're not seeing this issue all of the time, it may be something that might need service soon. We're not able to diagnose an issue remotely, however, you can run a diagnostic on your iMac. Use Apple Diagnostics to test your Mac

If you end up needing to have your iMac serviced, here's more info: Mac Service and Repair

Take care!

Hey Everybodyknows,

Thanks for the replies and info, we appreciate it!

Glad to hear that this only happens in the Photos app, and is not affecting the editing that you're doing.

When new macOS software is installed, your Mac does run through some system checks. This can sometimes cause hardware which is having issues to become more obvious.

If it becomes more bothersome, we'd suggest running that diagnostic and contacting Apple Support if it shows an issue. Get Support

In the meantime, go ahead and restart your Mac, as a restart can resolve unexpected issues. Log out, sleep, wake, restart, or shut down your Mac

Enjoy your day!