"TW 1.0" as I remember it - the first time I heard the TW term - was a thing where professors told students in advance if a lecture contained material that could upset some students, I think it started when someone teaching a course on criminal law in a law degree told students in advance "[TW:] next week we will have the lecture on the law around rape and sexual assault". Properly practiced, that's not exposure therapy that's being polite to your students (though why not put your whole syllabus up at the start of term, if you can?) It was also not intended to let you skip that topic - it's pretty important to know about if you're training in criminal law! - just to let you know in advance when it's coming up.
If you're teaching a course on the history of the British Empire in India, you're at some point going to need to cover the Bengal famine, the Amritsar massacre, the mutiny (aka. first war of independence), the practically-a-civil-war during partition, and a lot of other things. Mind you a "content note: British Empire" at the start of the course would probably cover all bases.
The choice of "trigger" that already means something in therapy was perhaps unfortunate, and nowadays I think "content warning" or even "content note" is preferred.
The real problem though was how students, who were neither trained therapists nor seemed to have consulted any, redefined and enforced their version of TW to the point that the term got tainted in the public view.
Basically, if you have anything like PTSD, you need an actual therapist not the collective hivemind of twitter (instagram these days?).