I recently got an email saying they had received a claim from the copyright holder, which seems strange as it is unlikely that the copyright holder would wish to identify themself.
The so-called "copyright holder" was actually a music publisher, and there was music in the video at various points, so I assumed it must be about that.
But I looked at the identified time section, and there was no music at all. It was just a guy talking. I have no idea why it matched.
I submitted an appeal. It gives you several options for why you want to appeal, but notably absent is "the video does not contain any of the claimant's material", so my "appeal" had to be submitted on the grounds that my (non-)usage of the claimant's audio is fair use...
YouTube's copyright system is laughable.
[0] If you're interested, this is one of my favourites: https://youtube.com/watch?v=BeeUXNF1H8s