Firefox on Android won't keep my "desktop site" toggle on - eviltoast

From what I’ve read online this shouldn’t even be an issue anymore since “desktop site” is meant to have been made default recently (edit: I was wrong this is not the case, see comments), but either way it isn’t for me, and I’m getting really annoyed at having to re-toggle every tab to desktop every time I open the app. I can’t find anything relevant in the general settings and both app and OS are up to date.
Am I missing something?