Don't know about auto-rejecting, but as a recruiter I'd run an AI checker if the text feels suspicious. Wouldn't risk it unless you're on a very tight deadline; why not spend the 15 minutes of writing the filler yourself?
> why not spend the 15 minutes of writing the filler yourself?
It takes away the emotional burden of writing cringe text.
What about cover letters though? Would an AI-generated cover letter look bad? From my perspective, the informational value would be the same or better, and I don't really have the time or desire to handwrite cover letters for each employer.