I mean, indeed every programming language has been made for a purpose, that's clearly not recommended to make software with PHP.
What do you want to achieve / what are you looking for ?
Python or JavaScript. I use async Python professionally and it works great. Would love to use Elixir for something, but I don't have the time to learn it right now.
(nah but fr, just pick any of them tbh. practically every backend just uses some general purpose language like C# or rust or something. just use whichever one you're most comfortable with, and that has a backend framework like spring boot that allows you to actually use it for that purpose.)