Where the bias isn’t obvious until you spend time on them.
The first examples I can think of are r/Canada and r/WorldNews
Yeah, I liked it there. I would never deny that the sun was left-leaning, because it inevitably attracted a left-leaning crowd. But it never silenced right wing opinions from what I recall. Downvotes, sure, but not deleting posts or unbalanced moderation.
They were never even telling right-wing people things like “You already have at least 2 other subs to discuss your views. Let us discuss ours here”, like places like r/Conservative say.