In essence, my perspective as a long-term user (five years this month) is that there never has been an established single practice for how and what to CW.

There are tons of different communities on here and all of them have different approaches to this, with a certain overlap (basically, CW anything that could be disturbing, retraumatising or that people may have other reasons to not want to engage with - for example if you're posting about discrimination against a group like PoC, trans folks or disabled people, and you're not a part of that group yourself).

So while there are some intuitive guidelines, and discussing best practice is always a good thing, it's simply bad optics when individuals put themselves out there pretending that their peer group's approach was the universal one that was generally accepted on the Fedi until two weeks ago.

There is no single definition of what constitutes "sensitive content". I do however believe that we can continue to make this place better by showing a healthy amount of respect for other people's boundaries.