I've been experimenting with AV1 using FFmpeg with SVT-AV1 for 2 years. I've encoded quite a lot of my videos in AV1 by now, mostly just animated content.

AV1 is really good for an open source project, no doubt about that. But after so long using it, I can safely say that it is really just good for storage saving with excellent quality-speed tradeoff, however, it lacks fidelity. My major discontent with AV1 has been how the encoder blurs some details completely out even when setting crf as low as 14 whereas HEVC doesn't at all. Edit: Also in some instances, particularly with non-animated videos, AV1 performed way worse than HEVC which I believe is due to it doing a poor job in varied and difficult scenes.

At first, I thought AV1 is only better for animated videos but later I found its really just any video so I've switched back to using HEVC for storage and decided to use AV1 only with preset 6 and fast decode on for mobile devices.

I don't mean to say that AV1 is bad, it does provide better quality than HEVC for sure but I wouldn't call that an upgrade when HEVC still has the major edge in fidelity.

It makes sense for VOD services to make use of it but personally, I wouldn't use it for anything except quick and super low bitrate encoding.... for now.