Here you go:
https://linux.die.net/man/8/named
This was installed as part of some other software (not a part or requirement of Pi-hole).
You can either configure named for a different port or remove it (but this might have implications further down the whatever installed it in the fist place).
Pi-hole required port 53 in order to work and if that port is not available, it will behave like it does in your case.