In reply to Ed.

Ironically I just found a stackoverflow article from 2019 with the exact same syntax: https://stackoverflow.com/questions/46425365/who-can-i-get-http-user-agent-of-gtmetrix-and-pingdom

My bet is this is not an intentional behavior to obfuscate things (why would you comment the php code then?) but more likely a copy/paste code from some online resource.