The line is obvious and well known:
- don't allow hate speech
- don't allow harassment
- reduce spread of (likely intentionally created) misinformation
The think is a lot of the complains come from people doing one of the points above _intentionally and knowing_ and then complain "but free speech". In their mind it is okay to spread hate speech and harass or push harassment of certain groups of people because they _do not see them as people_. They often also come up with stupid argument why their harassment is supposedly no harassment, with nonsense like "we should be allowed to always remind a traumatized person of their trauma because thats just free speach and purely informative we don't insult them" often taking advantage of 3rd parties potentially not understanding why its harassment far worse then some childish insults.
EDIT: Or complains from people which intentional spread misinformation for other political and often market manipulation reasons and don't like when twitter labeled their tweet as misinformation.