Proton is not a social medium. As to "how high", the lawmakers have to decide on that, hopefully after some research and public consultations. It's not an unprecedented problem.

Another criterion might be revenue. If a company monetises users attention and makes above certain amount, put extra moderation requirements on them.

Yeah, I work for your biggest social media comoetitor, why would I not just go post slop all over your platform with the intent of getting you fined?

Proton isn't social media.

If you can't understand why big = bad in terms of the dissemination of misinformation, then clearly we're already at an impass on further discussion of possible numbers and usage of statistics and other variables in determining potential regulations.