Two a month per submitter, starting now, and you can thank science slop for the change.
arXiv, the preprint paper repository, is seeing so many low-quality submissions, with AI tools helping drive the surge, that it has imposed a hard limit of two new submissions per month per submitter, regardless of whether they were produced solely by humans or with help from AI tools.
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Rate limit submissions -> people make sock puppet accounts -> rate limit account creation from same device/IP -> people use VPNs -> captcha
You need an existing user to vouch for the account on Arxiv nowadays, IIRC. So they have some tools.
I wasn't able to post a legit paper on Arxiv because I don't have the connections. Lame.