The echo-chamberiness of Lemmy is different from Reddit, but still a thing unfortunately. It'll really depend on the community you're in, but since the population of the Fediverse (and especially the Threadiverse) is very small compared to Reddit you tend to have the same people cropping up a lot. I haven't been banned from anywhere (that I know of - I don't actually know if I would get notified) but I find myself hammered with downvotes more frequently here than on Reddit when I say something unpopular.