You’ve obviously gotten the base level answer, but to add some color here - certain types of food, such as dried pasta, rice, beans, grains, high proof alcohol, vinegars, and basically anything frozen to name a few, never spoil in the sense that they’re unsafe to eat.
Flavor, however, is an entirely different matter. Just ask anyone who has eaten freezer burnt food.
Pretty much any high proof alcohol will fall into this category. And, if it’s unopened, it should retain most of its flavor for a very long time. Once opened, however, it can deteriorate relatively quickly, depending on how it was stored.
If a user is banned on their home instance, that ban is federated out to all instances. If a user is banned on a remote instance, they’re just banned locally on that instance, and their account remains active for all other instances.
They’re likely some remote users who have interacted enough with your instance to be federated over, and then banned on their home instance.