I apologize if the question is off-topic (but I think this is the most appropriate thread to ask about this).
Yesterday I came across a rather interesting case...
the joint's account is periodically online, but the latest publications are dated three years ago,
(which is rather strange). There are no signs of email changes, or notifications that the account has woken up after a long period of inactivity. Although I don't know how long such notifications are displayed, (
I would like to know more about it too).
This is the first time I've seen an account with such unusual activity. The account has been in read mode for three years... What do you think about it?

According to
theymos word the notification will be reaming for 30 days. So in this case I want to say did you notice that the account was not active in the last 30 days period? Or suddenly you saw it that the account is active?
So one thing could happen in this case, maybe the user came back a months or a few months ago but did not make any post. And if the user come months ago then generally maybe the duration of displaying such notification is expaired.