I'm also having this issue, also on aarch64, a Pinebook Pro:
I'm seeing RPi users with a similar issue.
Name Firefox
Version 89.0
Build ID 20210602080605
Distribution ID manjaro
User Agent Mozilla/5.0 (X11; Linux aarch64; rv:89.0) Gecko/20100101 Firefox/89.0
OS Linux 5.12.9-1-MANJARO-ARM #1 SMP Thu Jun 3 08:06:55 UTC 2021
Created attachment 9225490
firefox_video.png
I'm also having this issue, also on aarch64, a Pinebook Pro:
I'm seeing RPi users with a similar issue.
Name Firefox 1-MANJARO- ARM #1 SMP Thu Jun 3 08:06:55 UTC 2021
Version 89.0
Build ID 20210602080605
Distribution ID manjaro
User Agent Mozilla/5.0 (X11; Linux aarch64; rv:89.0) Gecko/20100101 Firefox/89.0
OS Linux 5.12.9-