No. All is served by the instance that you log into, and it consists of all of the communities that your instance federates with.
For example, if I make my own Lemmy instance I can’t find randomCommunity@lemmy.world in All until:
- Someone on my instance (probably me) searches for and subscribes to randomCommunity@lemmy.world
- It passes a check that lemmy.world is not explicitly defederated from my instance by me (the admin)
The only true “All” is Lemmy.Directory or similar instances that subscribe to everything automatically
deleted by creator