It's definitely worse and getting worse. I'm curious, do they not know this is happening, or not care? I struggle to believe people prefer the way it writes, which is becoming drastically different than its competitors.

I wonder if they’re training heavily on Claude generated content or conversation transcripts

Fable 5.1 was explicitely supposed to improve that, I used it only a bit so far and it seems at least better.

Maybe the humans are suffering from model collapse, and don't notice it.