Nextcloud docker stopped running & shows internal server error

I was running nextcloud properly and also used cloudflare tunneling to give it a domain for my nextcloud docker setup. But today I am unable to enter nextcloud using local or the domain name. I recently tried using pihole but do not know if it messed it up or not. I then disabled pihole completely.
Still I am unable to even get the login page of nextcloud. What could be wrong?

Can you access your data volume and look at your nextcloud.log file? That is where you need to look.