What are the most common reasons for Cloudflare blocking a user?

Cloudflare blocks users for a variety of reasons, primarily to protect websites from malicious activity. Common reasons include: repeated failed login attempts (brute-force attacks), suspicious traffic patterns (e.g., high request volume from a single IP), triggering security rules based on IP reputation (e.g., IP known for spam or hacking), violation of website terms of service, and detection of bot-like behavior. Specifically, Cloudflare's Web Application Firewall (WAF) can block requests matching known attack signatures.