I think the only time I've experienced this is when I had my phone off for weeks and still used Gmail. It spammed me on boot with tons of old email notifications.
Messenger is the worst for this especially since I only have my work phone on half the time so I tend to get a lot of old notifications for messages I've already read when I turn it on.
Is there a mail client you prefer, by the way? I've been pretty happy with Spark for a while now, but I don't care about their AI features and I'd really like Gmail tag support.
Ive started using iphones at the very beginning with nokia s60 phones. By the year 2012 I was overwhelmed by notifications and i started to adopt the policy "you need me urgently? Call me"
I have Disabled all notifications except for calls. I have no push notifications active and a great phone battery life.
I still use telegram for messaging but on my own pace (messages gets downloaded only when i open the app)
When I'm traveling and my tablet reconnects to wifi, I get a surge of vibrations. So the combo of notification sync and this feature sounds like it will finally solve that problem!