They can look up why you were blocked, your ISP, your local POP, the page you were requesting and if it was because of a firewall rule they’ll see that too. Basically everything unique about your request.

So if they’re accidentally blocking people because a firewall rule is misconfigured you’ll let them know.

In a previous job we used Cloudflare and found some of our remote workers were triggering a SQL injection on the website by updating our WordPress blog.