Is there a term/name/diagnosis for this?

I’m not sure how describe what I’m talking about…

Most of you are probably familiar with the infamous How is babby formed?????. Well, my question is about the answerer’s (well, and the asker’s) um, poor use of grammar and spelling.

I personally know of two people who are otherwise very normal and have average intelligence who write this way as well. They can speak normally, but for some reason, it never translates when they write. These are native English speakers, so not knowing the language isn’t the issue.

So, is there a term for this?

For the record, I’m neither judging nor making fun, I am just curious.