I'd guess some giant folder of mostly-copyrighted material, which happened to include those files for some reason.
metadata match on an album track number?
Na, it’s gotta be something dumb on the big G’s part. I bet their unit tests for their DCMA search have test cases with simple files like 1 and 0, and those cases are just put into the “copyright” database.
It's AI. Automated Ineptitude.
"A review can not be requested for this restriction."