The first commenter is absolutely correct; if I saw a comment on a post that read “Please kill urself aren't u ashamed ugh” I would read that as strictly insulting. Tone is something even native speakers of English, and I'd assume speakers of practically all other languages as well, sometimes have trouble with. The exception would be if there was some sort of emote or contextualization added that made it seem tongue-in-cheek, like your example sentence with the parentheses (which would read as you intended to a native English speaker).
We rely on tone, micro-expressions, and all kinds of verbal and non-verbal signals to subtly convey meaning when we speak – many of which we're not even conscious of – and it's important to remember when we write online that none of those signals will come across. Your reader can only read the text on the screen. We also don't have the goodwill of our partner(s) in conversation like we typically do when face-to-face, which can make misunderstandings come easily. I'd err on the side of caution – if you want to act clever in a comment section, you should include something other than the face of your comment that makes it clear. For example, you could use a quick clarification by parentheses or a dependent clause, or by just adding a short post-script sentence to let people know you're not serious. You can also use emojis, but they can also be misread if you're not careful – a laughing face could read as callousness instead of good humor, for instance.
Once you feel confident enough in your English-language skills, you can begin to rely on your understanding of the subtext of your word choices and phrasing. One of the great aspects of English that makes it so expressive (and so hard to learn) is how many word choices you have from different language and literary origins. With practice, you'll learn that many words and phrases are the same or similar on their face, but will read slightly differently to a native-speaking audience.
Then again, you can't ever go wrong with saying exactly what you mean.
Louket
“Please kill urself aren't u ashamed ugh”
“I am mentally ill”
“Ugh go die plzzzz”
“Delete this”
If you're seeing this on TwitterX, the meaning is probably straightforward. For some reason everyone has decided that it's okay to threaten if they don't like something or someone.
Precipitation24
Really? While writing this article, I never doubted that what the original poster said was correct, but as you said, it certainly seems possible that what he or she said might not be accurate.
Incidentally, the OP said that this phenomenon was first observed on TikTok.