Desktop Firefox is also a mobile Firefox on GNU/Linux mobile platforms though.
So the “mobile Firefox” there isn’t really a mobile Firefox just the desktop browser used in a mobile context? Or does Mozilla support such platforms in any official way?
Even the Android Firefox app just got fairly recently rebuilt, mobile isn’t really Mozilla’s strong game after they shut down Firefox OS (which though strangely lives on as KaiOS)
Also: Both Android and Jolla are also Linux based
AFAIK the kernel plays practically no role in how a browser works.
On your comment though: I think maybe MacOS Big Sur disagrees with you: https://twitter.com/voxpelli/status/1343323353294262272?s=21 Not sure if kernel level or other level, but it sure has made eg VS Code pretty slow for some people ;)