They use scammy providers like Bright Data[1] that let app authors embed their malware (for a compensation, I'm sure) which turns users' devices into crawler proxies.
> So by blocking these IPs, you are blocking your users.
There were 122 million residential internet connections in the US in 2024 so for an app with 1 million users the chance of affecting a single user is <1%.
[1] https://docs.fcc.gov/public/attachments/DOC-411463A1.pdf
So by blocking these IPs, you are blocking your users. (ie: in many coffeshops, I get the "IP Blocked" banner, my guess is that they are running software on unsuspecting users to route this traffic).