With containers, most will have a persistent volume that is mapped to the host filesystem. This is where your config data is. When you update a container, just the image is updated(pihole binaries) but it leaves the config files there. Things like your block lists and custom dns settings, theme settings, all of that will remain.

There is plenty of propaganda on lemmy. You just have to realize you will always be fed propaganda and understand there is propaganda on each side of every issue…