Automatic groups are intentionally hidden from the group index (/g) — but the visibility settings will let normal users visit them directly (community.example.com/g/trust_level_0).
It’s been like this for a long time… there’s an old comment in the code about why
# hide automatic groups from all non stuff to de-clutter page
but maybe it’s unnecessary now? might be clearer to just have them follow their appearance settings (and let them remain hidden by default)