Is “there” and “they” being used instead of “their” a new rebellious slang or genuinely a lack of knowledge for grammar?

I’m not sure if it’s the Baader-Meinhof phenomenon (see it somewhere and then suddenly start seeing it everywhere) or it’s a new emerging way of typing I see almost in every single comment section/post.

For example “Somebody tell them they stuff is taken” or “I dropped it off at there house”

It’s everywhere I’m losing my mind lol. I was thinking of asking this entire week and after seeing it THREE TIMES today (and it’s barely afternoon!) I’m finally making the post. Anyone else notice???