Incredible. I just changed my user-agent whilst on the Google Chrome browser.
* Changing to Firefox immediately displayed the Cloudflare error message
* Edge had no errors
* Chrome had no errors
* Safari had no errors
Edit: Even internet explorer 9, android kitkat, and the opera browser had no errors.Edit 2: as another user has pointed out, this is most likely a firewall rule put in place by the website operator themselves.