ntfy never really had good push to iOS, in my experience. The only way I could keep my private channels consistently working was to use the PWA and specifically not sign into it (otherwise, my login token would expire and break things).

I gave up and switched to pushover and as long as I’m somewhat cognizant about what i’m including in the notifications, I’ve been pretty happy.

I’d love for something self hostable to get as good as pushover on iOS