If you don't see it under the device's settings, look for a general notifications or alerts section in the app

where you can often toggle motion-related alerts on or off.

If the app has notification brutes or modes, you might have turned on a specific alert profile.

So I'd suggest digging into the app's notification settings rather than the device-specific page.

If all else fails, some apps even have a global notifications toggle you can adjust.

Let me know if you need more help hunting it down.

Yeah, I thought I might turn off the notification permissions for the app altogether,

but it doesn't really solve things because there may be some other notifications I do want to get.

So I've gone in notification settings and I can see device alert is toggled on,

but I can't see where I would have specified which devices to alert for.

Ah, that's a bit of a puzzle.

Some apps bundle all device alerts together, which can make it tricky.

If the app doesn't offer a per-device...

device alert setting in the obvious places...