Consider passing a public DNS server into your container:
services:
pihole:
ports:
(…)
environment:
(…)
volumes:
(…)
dns:
- 127.0.0.1
- 1.1.1.1
(…)
That may fix gravity updates and should allow creation of a debug log.
Pi-hole definitely needs port 53, so any other service claiming it needs to be stopped, unless you'd run your Pi-hole container in macvlan or ipvlan network mode.