Unsupported Photo Library
I'm running a MacBook Pro Retina 15-inch, Mid 2015. I was running Big Sur when I tried to upgrade to Monterey, but that was an absolute disaster. Had to take my Mac to an Apple store, where they wiped it clean and reinstalled Big Sur 11.6.1 (I decided I didn't have time to wait for Apple to get the bugs out of Monterey). Big Sur had been working just fine. Now, when I open Photos, I get the following error message: "Unsupported Library: The library 'Photos Library' is from a newer version of Photos. Please upgrade Photos to open this library." However, I cannot find a newer version of Photos, and when my system checks for updates, it doesn't say I need to update Photos. I'm at a loss.
MacBook Pro 15″, macOS 10.12