I don't know how to fix this easily.
Topic on Template talk:Middleware
The "anticheat" parameter is not intended to hold anything other than the clear-text value. Any reference goes into the notes field.
See Albion Online as an example:
|anticheat = Easy Anti-Cheat |anticheat notes = <ref>[https://www.easy.ac/en-us/partners/ Easy Anti-Cheat]</ref>
This applies to all parameters — the notes field is generally where references goes if a dedicated "ref" parameter does not exist for that template. The "main" parameters are kept free from all stuff like that since that's what's going into the backend logic and databases (and an incorrect value, such as a value followed by a reference, screws up the logic).