Yes, known bug but I realized I didn't create a ticket yet

It has to do with how push services behave. They may update your push subscription at any time and we have to update the push subscriptions of users in that case but the code which does that doesn't seem to work and isn't obvious to test. But I think it only requires some more research. We will definitely fix this soon-ish.

If someone is knowledgeable about this stuff and wants to look into it, this is the code: https://github.com/stackernews/stacker.news/blob/master/sw/index.js#L66-L97

edit: Created a ticket now