Any hosting provider running cPanel is running on Perl

Perl used to be a really popular language for cgi scripts. So much easier than writing them in C! I can't describe how amazing PHP was at the time of its inception. While I have trouble picturing somebody starting a big website in perl today, it's certainly plausible that momentum prevents a switch pretty much indefinitely.

some of the older stuff at OVH is also in Perl.

All the newer stuff is in Go or Python (thank God), but there's an acrophyal story about someone asking Octave Klaba, the founder of OVH about any regrets he had, and he allegedly responded "maybe using Perl was a bad idea".