I must admit the style of language used on this forum is indeed more formal than I would expect most of my generation to use!
A typical response from my generation might be something like:
Young people today tend to abbreviate, use shorter words, and have almost adapted a “neo-English” which includes said abbreviations which are (to them) universally known, and generally includes less complex language.
I must admit I really do notice the difference in my own linguistic style when texting uni friends vs using the forum!
Personally, I find it physical painful to write stuff like that (so I don't!

). Probably not helped by the fact that I'm unfamiliar with a decent proportion of these modern acronyms (along with other modern phraseology and terms. For example, "TERF" seems to come up every now and then, a term I'd never come across before university. I had to Google it ("trans-exclusionary radical feminist", in case anyone's wondering).
Another anathema amongst the younger generation (and to a lesser extent older generations) is incorrect (or missing entirely!) punctuation and grammar, which again is something I just can't do, with the exception of not putting a full stop at the end of the final paragraph of a body of text I'm writing informally. Like so
(Although really there should be an exclamation mark here!)
I tend to use 'hi' in texts to friends and family, excepting one person who would deprecate it.
I prefer "hello", for some reason "hi" doesn't sit comfortably with me and I genuinely don't think I've ever used it in speech (which is probably why I prefer "hello" in text, although it does occasionally sound a bit formal, in which case I may type "hi" instead); "morning" etc is my go-to informal greeting
reciprocation...
There's one we can add to the list!
I think we can add deprecate to the list; I don't think I've ever heard anyone say that!
I beg to differ (does that count?): deprecation is, whilst not exactly the most common term in my vocabulary, a reasonably frequent utterance (and typeance, if that's a word!) of mine