In a world without dark design patterns, there would be a single pop-up when you first install the application, to ask if you want notifications and/or suggestions for new features. If you click "no", it should never bother you again unless you go into a menu and opt in. Anything beyond that is inherently predatory.
Ideally, that pop-up wouldn't even exist. They could just have a collective "don't bother me again" checkbox on every non-essential notification, so you can easily disable it the first time they become relevant. If your user has already indicated that they are not interested, any further pestering is essentially harassment.
If the user has indicated that they are not interested in new features, it means they do not care about new features. They don't want to know about them, or they prefer to find out proactively in their own time. If you still insist on ramming notifications down their throat at that point, you're not doing it for the user. You're doing it for yourself.