From what I can tell, it seems to be notification of new posts in your subscribed communities. I know it seems like a lot, but remember that Lemmy used to have about 100 active users 18 months ago. Having 50k users is a pretty recent thing, and definitely happened after this option was added.
I've enabled it and will report back once I get a notification.
Came to post that I just tried to activate the setting out of curiosity (on lemmy.ml and lemm.ee), and there seems to be a block against it.
The following message appeared in the browser console:
The Notification permission may only be requested from inside a short running user-generated event handler.
So I'm guessing it got turned off at some point or it's optional for instance admins?
How certain are you of what it's supposed to do?
Did it actually register in the settings for you? (When I tried to activate it and save, lemmy sort of updated itself without the setting on ... that may have happened to you too)
The following message appeared in the browser console:
I don't get this, but also I have already blocked browser notifications so maybe that's why I don't see it. My assumption though is that the notifications aren't only browser notifications, but follow the normal Lemmy notification process of browser (if enabled), notification icon, and email (if enabled).
Did it actually register in the settings for you? (When I tried to activate it and save, lemmy sort of updated itself without the setting on … that may have happened to you too)
It didn't! It clears when I try to turn it on. I didn't notice the first time!
How certain are you of what it’s supposed to do?
Not at all! I just read around some old github issues, but to be honest I never saw anything concrete.
So I’m guessing it got turned off at some point or it’s optional for instance admins?
I'm an instance admin, so it's not that. On Beehaw (running previous version of Lemmy, 0.18.4 instead of 0.19.5) it lets you enable it, so it must have broken somewhat recently (in the last 6 months). But I didn't seem to get a notification despite a new post appearing in a community I'm subscribed to.
So now I'm even less certain of what it is than I was in my first post, when I wasn't very certain.
FYI, a Lemmy dev confirmed this setting doesn't actually exist in the database anymore. A relic of times gone by, and it's going to be removed in the next version.