The built in web server is awful on its own. Forget production usage, it’s hard to even use for a quick bit of E2E testing.

Unfortunately it has some really opinionated routing rules with certain file extensions, preventing you from having a dynamic URL with something like a .json or a .xml extension. Instead it will always try to look up a static file of that and serve it instead.

I can’t find the bug tracker issue for it but it was closed out with a message along the lines of “don’t use the built in web server for anything besides a toy”.

Luckily there are plenty of PHP Cli based web servers now that some other commenters have mentioned.