Are you running the version from your Ubuntu or SNAP? Can you download a separate copy of Firefox to a folder, run it to see if the option is there? I see the option. see screenshot

Operating System: openSUSE Tumbleweed 20210114 KDE Plasma Version: 5.20.5 KDE Frameworks Version: 5.78.0 Qt Version: 5.15.2 Kernel Version: 5.10.7-1-default OS Type: 64-bit Processors: 8 × Intel® Core™ i7-4810MQ CPU @ 2.80GHz Memory: 31.0 GiB of RAM Graphics Processor: Mesa DRI Intel® HD Graphics 4600

Is DRM available on firefox for armhf?

I just googled your question and look what I found.

https://bugzilla.mozilla.org/show_bug.cgi?id=1392037

Just as test can you download a separate copy of Firefox to a folder, run it to see the option is there. Try beta or nightly.

https://www.mozilla.org/en-US/firefox/all/#product-desktop-release

Ok i will try the nightly version

Installed latest firefox beta but same & firefox nightly isn't available for armhf

You need at least make sure you install Widevine for ARM64.

See e.g. threads like these.

• https://forum.vivaldi.net/topic/42353/widevine-not-working/12

Widevine for Chromium or Firefox

• https://www.raspberrypi.org/forums/viewtopic.php?t=233664