As you might notice, the new comments are shown YELLOW, that’s not a bug, it’s apparently a new feature in Lemmy…
I made the feature request to add incremental reading , but the method they use seem like non of the methods i suggested (I think it highlights all comments after X minutes) and I think that is a way that is useful to no one, If the instance owners of lemmy.world think it is not good maybe they could provide feedback on the issue, or at least request an option to disable it, the owners seem like they are in a good position to collect feedback.