The only subreddit I've ever been banned from in 20+ years is /r/comics. Lifetime ban for a single offence of questioning a comic strip. According to the mod: "This is a fan subreddit, this is not a discussion subreddit." There's plenty of discussion on there, but I now realize it's highly filtered. It took me too long to figure that out because it mostly aligned with my views up to that point.
We're in bubbles everywhere now. Enforced by mods and payment processors and social networks. I'm now much more careful about what I post online. We don't have an actual public square to discuss things.