I don't believe there are any logs being transferred, just the abusive IPs are shared with the central DB.

So if an IP starts hitting a ton of rules (like .env access, repeated 403s, 404s, 429s, etc.. Or specific AppSec rules) then that IP is blocked and sent to their central DB where it's pushed out to everyone running crowdsec.

On my setup crowdsec has been more effective than cloudflare at stopping scanners and bots from overloading things, cloudflare just lets basically everything through so I stopped using it.

That said I'm curious if you remember the source of the real world tests, because I'd love to see what's actually better.