Determining what encoding to use

I just recently upgraded my unraid server to 7.0.1 so I can finally take advantage of an Intel Arc A310 I bought last year. I setup a tdarr flow from this guide: https://github.com/plexguide/Unraid_Intel-ARC_Deployment

Then I started testing and tweaking it a little (I set the CRF to 22 instead of the flows default 29) and was happy when I thought "I wonder how this flow would work with HEVC on my current and old cards" since I have both in my server ATM.

Well, unexpectedly HEVC is more efficient at compression and it looks the same to my eye (I can provide screenshots upon request).

From everything I've read AV1 is the best, so why is my HEVC compression with my Arc card better than AV1?

https://preview.redd.it/c78ostmdhqpe1.png?width=2021&format=png&auto=webp&s=f3b06e8ba53bb81a36dd158d1b14731eee9f144e