24562972people upload their 1080p footage to YouTube as 4K to get 'vp9' compression (less aggressive compression) vs the standard avc / av1.
For the record, AV1 compression on YouTube, unlike AVC, can be even less aggressive than VP9.
A rule of thumb here is pick AV1 video tracks if their bitrates are comparable to VP9's (or slightly smaller, but not more than √2 times smaller).