Unfortunately the problem is still present even with libnss3 2:3.70-1 and firefox 93.0-1+b1.
I will try some more stuff like downgrading more packages and creating a new firefox profile to see if it not just a problem on my end. I will update if i can find anything. Still strange someone else reported something vaguely similar in about the same time period tho. Also never seen something like this happen and i've been using firefox (/iceweasel) on testing for many years.
