Comment by koito17
This was indeed one mitigation used by a site to prevent bots hosted on AWS from uploading CSAM and generating bogus reports to the site's hosting provider.[1]
In any case, I agree with the sarcasm. Blocking data center IPs may not help the OP, because some of the bots are resorting to residential IP addresses.
Ya if it's also coming from residences it's probably some kind of botnet