Why do I keep getting my feed filled with communities I already blocked?

just because you blocked !worldnews@lemmy.ca doesn't mean you also blocked !worldnews@lemmy.net.au !worldnews@notdigg.com !news_world@lemmy.link

yea, it is annoying.

Maybe communities on different instances? for example there's quite a few gaming communities titled "gaming" that exist on different instances

Do you instance jump? Blocks on one != blocks on another

Pro-tip: block using keywords. Some instances also are defederated from others, meaning you don't see their comments or posts.

What do you mean by channels? Video channels (for example in Peertube) or Lemmy communities?