Thank you.
I must’ve done something similar.
I removed the integration for my iPhone (was in there twice), removed the app from my phone, restarted HA, reinstated the iOS integration (logged in via the app), restarted HA. Reset the notification settings in the app.
Bit of a heavy handed approach. But it came good eventually.
The other phones continued to work throughout though.
I appreciate the response. Your recommendation was much shorter than my method… 
I just updated the app too and now have no notifications.
I also now have two identical iPhones showing up in HA.
Where do I delete them from?
In all other respects, the app works fine including watch actions.
Is this is still a problem for you?
Sorry just saw this post…
Thank you, @CrouchingWorm, all sorted now.
I deleted all iOS devices, reinstalled the app, and all is good.
Good to hear… NP.
So this means you had to disable Pi-Hole when installing the HA companion app and registering the device, right?
In other words: disabling Pi-Hole for the moment of actually sending notifications was not sufficient?
(asking because of Notifications sent but not shown on devices (cross-platform issue for Android and iOS devices))
Managed to fix it for the iPhone (see Notifications sent but not shown on devices (cross-platform issue for Android and iOS devices))
BUT for Android this is not working, my device still does not receive/show any notifications 