In my short time on Kbin vs. Lemmy, the communities seem quite different already. Kbin reminds me of Reddit today: lots of one line answers and sarcasm, some rude comments too. Lemmy (and Beehaw) so far seem more genuine with more thorough discussions and feels like Reddit did 10 years ago.

I assumed it happened when someone on your instance subscribed to a new community for that instance so it loads in all the posts since they are technically new. Definitely a bug

This has been bugging me too, especially on mobile. Going back after reading a thread and it takes you to a completely different place.