Reasons why using Cloudflare (their reverse proxy offering) is terrible for the end-user:

• Annoying load-times for users of a website
• Sometimes annoying captchas for Tor users (not as prevalent as it was a few years ago)
• Strings that look like email addresses get censored by Cloudflare, such as Mastodon usernames for example
• Cloudflare fingerprints your browser with JavaScript and cookies which results in:
  • Bad privacy for the user
  • Terrible accessibility for browsers or other web clients that don't support JavaScript or cookies or have either of them disabled
• Cloudflare is able to see everything a user does and sends or receives on the website, including sensitive data like login information
• Cloudflare is used as a reverse proxy by lots of websites
  • it is therefore able to do user tracking on a huge scale
  • when Cloudflare has a technical issue, a big chunk of the internet could become unreachable