I got once a copyright claim on behalf of Antonio Vivaldi, at first I was like "WHAT??? You can't be serious, who the •••• owns Vivaldi's copyright?!?!?!" But

I got once a copyright claim on behalf of Antonio Vivaldi, at first I was like "WHAT??? You can't be serious, who the •••• owns Vivaldi's copyright?!?!?!" But the record label that issued the claim answered promptly to my counterclaim and the video was restored in 24 hours. My supposition is that record labels upload thousands of songs to the Content ID system without checking them first, and they correct the copyright status of songs with the counterclaims they receive.