Firefox does not play videos above 4K, also on the demo website

[ImRidingNow]

Does work:
https://docs.bivrost.pro/webplayer-docs/resolution-4096x2048.html

does not work:
https://docs.bivrost.pro/webplayer-docs/resolution-8k.html
https://docs.bivrost.pro/webplayer-docs/resolution-8k-h265.html
https://docs.bivrost.pro/webplayer-docs/resolution-8192x4320.html
https://docs.bivrost.pro/webplayer-docs/resolution-8192x4320-h265.html

Error:

FYI:

All videos work in Brave and the Edge browser, and both are Chromium.

Firefo Version: 127.0.2 (64-bit)
Happens on two tested systems with windows 10