Why am I not receiving notifications after updating to iOS 15.7?

Almost two weeks ago, I updated my iPhone 11 to iOS 15.7 after receiving word of a security vulnerability. Since then I am only receiving notifications for phone calls and texts, with some WhatsApp messages sporadically appearing. Crucially, I am not getting notifications from my Gmail, Outlook or Teams, but I am not getting notifications from lesser priority apps either. I have tried rebooting the phone, checking that notifications are turned on in each app, and even updated to 16.0.2, but none of those fixes worked. I tried resetting my iPhone and that hasn't worked either. This is getting frustrating- what else can I do?