So I just changed the OS of my server from Raspbian to Ubuntu 19.10 on my Raspberry Pi, along with a new 6TB WD Red, which I migrated my data to.
I was getting an internal server error, and I don’t know exactly how I solved it, but I thought that switching the entire Nextcloud data to www-data:www-data would solve it (along with 750). However, when I recursively changed the owner to root:root, that solved it. However, I remember there were folders that were owned by www-data:www-data, when I was still using Raspbian. Did something change?