@urbanbirdbud you can tell if someone is from another instance if a/ you cant follow them or b/ they have a link behind their username that tells you which instance they're from (eg. @sentiniel).

if you're looking at tags, instances shouldn't matter too much aside from following people. however, since each instance has their own federated/local timeline, you may find posts that could be alienating (eg. being on tabletop.social when you're not a tabletop player).