Any changes made as a result of this issue being resolved may not be rolled out here until later.Changes to allow certain URLs which do not have a trailing slash to work in a more predictable way.
@Chris DThe changes have been rolled out here if you want to test them.
To demonstrate the fix more clearly...
http://1c25e54a9cf83044.demo-xenforo.com/214/index.php?tags/php - Results in a 404
https://xenforo.com/community/tags/php - Loads correctly