They just communicate digitally in such a distinct way.
Surely it’s something you’ve noticed as well. The way you can tell, just from a written message, whether someone is old or not. Or just, you know, not intimately familiar with generally accepted digital mannerisms. Not even just writing style, but also the jokes they attempt to make. Learning about common message formatting one thing, learning how to make jokes that actually convey well is a whole other beast.
It’s like watching tourists trying to fit in with the locals, you know? And that’s not that surprising. The internet is basically its own continent, so of course you’re going to find many strange new cultures. And just like in real life, trying to follow some guide to try and fit in makes you look even worse: fakey and off.
You really have to be born in it, molded by it.