"Trauma Dumping" is an extremely inconsiderate term and needs to be de-normalized
One of the most inconsiderate terms I've come across.
You can say that mental health sufferers should seek appropriate healthcare, which I agree with. But sometimes that is not immediately accessible and/or you just need someone to listen to you with empathy.
The term is usually used by selfish and unempathetic people who believe that anything that doesn't affect them is not their problem and they should be shielded from the realities of other people's suffering.
The word "dump" itself is extremely inconsiderate. In most cases, they are not "dumping" for the sake of dumping, they are trying to get out of the emotional pain they are feeling and often times it is a cry for help.
If you frequently use this term, I will assume you are a selfish and possibly narcissistic person and I would make a conscious attempt to not form a meaningful relationship with you. If I ever go through an unfortunate life event (which is kind of inevitable), you would probably break away when I bring it up anyway.