That was also the case for me (FF for Android), and I eventually found that I have WebGl disabled by default. Everything worked as expected after I resumed. FF animations run quite smoothly. Good work for developers.
Thanks for the bug report. We'll have to figure out what could be causing this issue.
I experienced this in Librewolf as well, it happens when WebGL is disabled. Should probably present a visible error to the user when this happens.
To be precise, Mull browser (a Firefox fork).
Mull probably has WebGL disabled as an anti-fingerprinting measure.
I had to switch to Edge to get it to work.
Can't find that damned access token though.
Check the storage room accessible from the main "hub"