Have you adjusted the splendid mode? This issue is caused by the new version of google photo album. It is recommended that you adjust splendid back to standard.
Update to the latest version 18.104.22.1683439869. This issue has been fixed now.
I am using Wide Color Gamut, but didn't have problem with brightness increasing and decreasing when browsing and zooming in photos. I can switch from Wide Color Gamut to Standard mode and back and still have no problem at all. I wonder what is the trigger of this issue.