The abuse of terms and words in languages is nothing new, but got worse with the Internet. Imo.
Words used figuratively, like "toxic", are then used again in a furthermore figurative way derived from the first figurative way (which makes it already very vague), and replace words and terms that do already exist and are, actually, much more efficient and precise to describe a person or a situation.
What is toxic, originally means what does poison your body.
Then, and that I understand, it has been used to describe a relationship where two persons will keep hurting each other (usually in their feelings) until, possibly, the mental health of one of them (or both of them) gets threatened.
What I don't understand so well, is the use of "toxic" to describe someone being merely annoying, gross or rude. With "toxic", one can't know which the person proved to be. And maybe it's not always exactly the same thing, and then doesn't call for the exact same reaction... Idk. (and hey, is a beatup "toxic"?)
One of the ideas implied by the figurative use of the term "toxic", is that it doesn't show at first, that the thing, or the person, is harmfull. But maybe I'm wrong.
Well, if, in the end, everybody and everything will be separated between "toxic" and "non-toxic", one could aswell just say "bad and good" don't you think?
Anyhow, it's nothing important, I just wanted to share my thoughts on the subject, and I do apologize if some will find it off-topic, boring, or... toxic? (lol).
There are always rude people whatever the game, just go with it