Android 13 question

[John F. Eldredge]

I recently upgraded to a Moto G Stylus 2023 (4G version). It is running Android 13.

Every 30 seconds or so, a light blue, translucent band appears, moves from the bottom to the top of the screen, and a chime sounds. If the phone is set to do-not-disturb mode, i get the color bar but no chime.

This chime sound is NOT what I have selected as my default notification sound, and no notification appears. Does anyone have a suggestion on how to fix this? It is very annoying.