Nobody said we were polished. We're literally the upstart underdog.
It is known about, and it's being worked on, but since it's ultimately an open source project, there's no deadline provided for when it will be fixed.
Luckily it's not a big deal, it doesn't prevent the pending subscriptions from showing up in your feeds. If it bothers you just wait for your server to be not busy, unsubscribe and resubscribe, should take care of it.
There was a different vulnerability found that let the attacker take full ownership of a compromised account - some moderator and admin accounts were compromised. I would prefer the developers fix that first.
Functionally, it doesn't cause any problems. It'll show up in your subscriptions with the pending showing. It's just horribly confusing until you find out that it's a visual glitch rather than something functional.
And, it is mostly .world that does it. It isn't exclusive to there, but it does it more than any other instance, and it does it almost all the time.
LemmyWorld is under a lot heavier of a load than most other instances, so they're a bit more prone to delayed sync issues, I've noticed. That'll come and go as the LW admins mitigate their load.
I really wish that the more specialized communities on LW would find different instances to migrate themselves to. LW should just be more of a "generalist" instance, since they're seen as the de facto "hub" for the Threadiverse right now, so anything to help move some of those communities onto instances that can handle them better would be great.