Since my Peertube instance was down for a few weeks I am not entirely sure when this happened, but I suspect something in Peertube version 8.2.x changed regarding the ffmpeg settings that broke hardware accelerated video transcoding.
It still works for VOD and livestreams work with the default CPU transcoding.
I suspect the plugin I use became somehow incompatible, but if anyone here has similar issues that might narrow it down further.
Im not sure, havent had the issue, but im a bit behind on the versions now. Maybe someone else can chime in?
You should really update as there have been some serious security issues with Peertube.