Are you able to test server version 1.32.5.7349, which is the latest stable release?
I have a system running a similar CPU configuration (Celeron N5105) and the latest beta server (which you are running) has broken hardware accelerated transcoding again. Backing down to the stable release corrected the issue.
You may want to go ahead and turn on debug (but not verbose) for your server logs and include a fresh batch; @ChuckPa is going to want them. And no snippets, full logs.
Finally, if you can downgrade to a 5.19.x series kernel for troubleshooting, my crystal ball suggests that’s going to be requested as well.
