It is a huge problem. I wrote about it last August, too. I'd been a pub editor for a while, and found them via submissions.

How are you finding them? It feels like hunting for a needle in a haystack. Is there some simple way to check other than the paid version of grammarly?

Maybe if more of us were checking and posting, Medium might have more motivation to deal with it.

One simple way would be to limit publishing to paid members. Don't know why they don't do that.