This could - perhaps - be an effect of recent changes in upstream mesa source.
- The disabling of hardware codecs in community distributions [LWN.net]
- Upstream mesa removal of AVC/HEVC/VC-1 hardware acceleration (AMD GPUs)
- Getting Hardware accelerated decode in various software in manjaro after recent changes in Mesa
You can find a very recent mesa build I made for myself at https://nix.dk