Nextcloud 30, Traefik, Cloudflare, Real IP

I would recommend checking the logs. You can find how to adjust Apaches log to show the client IP and proxy headers here:

If you see the client IP there the problem is inside of the container if not on the cloudflare infra.

UPDATE: I feel this issue could be interesting (not the same problem but CF and real-ip) https://github.com/nextcloud/server/issues/45450