I think the developer can change the notification channel ID (which they use to group similar notifications and the user can disable a specific channel) and then you basically start with a channel without previous settings. You would have to disable all notifications for an app completely (not just a specific type) to prevent this for the future.

Or, you know, delete the demonstrated-untrustworthy app from your device...

Thats what bothers me the most about my Samsung phone. Facebook came preinstalled and I cannot uninstall it. I can only deactivate (whatever that means).

I don't use facebook, I actually never did. Its not the fact that I'm loosing a few MBs of storage that really bothers me, it's the fact that this is the facebook app.

You can uninstall it using ADB, even without rooting. Not a consumer-friendly solution but I’m throwing that out there in case you want to try it.

I think I'll try that. I guess that'll work for LinkedIn/Office as well? However, not sure if the BYOD policy will like that.

I don't have it on my phone and I don't see a reason for a native app for facebook. The mobile website works good enough if I need to check something (sadly it's heavily used also by companies and newspapers in my country) and messenger works through https://mbasic.facebook.com/messages/

That's actually what I ended up doing to 'fix' it. It's disappointing, yet not surprising, to learn it's intentional subversion of the API.