Grabbed an old laptop with an i5-4200M. I confirmed that I have H264 hardware decoding after I followed the wiki and checked with vainfo.
I installed Brave from aur (brave-bin) and performance tanks when playing a YouTube video. I checked it and is using a software AV1 encoder.
Is there a way to disable that? I checked brave://flags and disabled the only AV1 option, but it did nothing.