In Portuguese we don’t use many acronyms, but we have shorter versions of words with the vowels removed or things like that. When people tried to use acronyms we ended up with “fds” which some people read as weekend, others read as “fuck it”. The only other acronyms I can think of right now are all for offenses such as fdp (son of a bitch) and cdf (“ass of iron”, very old term for calling someone a nerd).

Not necessarily an acronym, but here’s a fun one for Japanese: Laughing in Japanese is warau, which gets shortened when typing to just w. If you want to laugh a lot, you would type wwww. That ends up looking like a field of grass, so that in turn gets shortened into 草 (kusa, or grass). Basically, 草 is the Japanese equivalent of lol

Also, in Chinese, thank you is often abbreviated as 3q, because when you say it out loud, it sounds like “thank you” (san kyu)

ex-USSR early rusophonic internet had a lot of original and transliterated ones but I rarely see them nowadays, and most are community-specific. Some didn’t carry over, some replaced by chat stickers, and the writing\reading of longer posts itself seems like a niche now when there are audio and video messages at hand. Add there that the web space I talk about is now also fragmented and occupied by bots\dummies due to the war and many sites for international communication on russian lost a big part of frequent posters\mods and later effectively musk’ed themselves.

Those I’ve heard the last:

imo > кмк > как мне кажется > what I suspect is
bf > мч > молодой человек > young partner
wtf > чзх > что за хуйня > what's a dickshit
idk > хз > хуй (его) знает > dick knows (that)

A lot of newer words I googled after hearing it from kids came from TikTok and they are mostly translations of trends carried in by local influencers.

French :

ftg : ferme ta gueule (shut it) ntm : nique ta mere (fuck your mom) slt : Salut (hello) cv : ça va ? (How are you?) ptn : putain (fuck) srx : sérieux (really?) jpp : j’en peux plus (I’m fed up)