"Until now, someone wanting to submit to arXiv for the first time only needed an email address affiliated with a reputable academic or research institution, such as a university. But a rule instituted on 21 January now requires first-time posters to be endorsed by an established arXiv author in their own field. People who have previously posted in the same disciplinary section of arXiv do not need an endorsement.
The move is an attempt to clamp down on a rising tide of fraudulent submissions, says University of Amsterdam astronomer Ralph Wijers, chair of the arXiv editorial council. A large fraction, he says, are generated with artificial intelligence (AI). The new rule is “mostly to try and discourage very junior, unskilled people from trying to get something started by sending some rubbish to arXiv,” he says."
https://www.science.org/content/article/arxiv-preprint-server-clamps-down-ai-slop