I've had the same problem multiple times over the last week. My phone is a Pixel 10 Pro XL, so it's not an iPhone issue, and it is affecting both my phone and my wife's.
Turning notifications off and on again in the app DOES NOT fix it. The only solution I have found is to uninstall and reinstall the Google Home app on each affected device, and then when it is reinstalled the notifications start working again. I've now had to reinstall it twice on my phone in the last week.
Curiously, if you press the doorbell to ring it smart speakers chime as normal, but the notifications don't reach the phones, so it appears to be an issue either with the Google Home app or Google Play Services.
