My Samsung J3 (specifically SM-J330FN) has suddenly started giving a curious double-vibration at random intervals. Since I never know when it's going to happen it's difficult to listen closely to the effect, but both sounds are very brief and of the same duration.
Notification reminder is switched off and I can't find any other setting which would produce this. The phone is running Android 8.0.0.
Steven, thanks. I had wondered about that but can't for the life of me identify the culprit, especially given that it started only a few days ago and I've added or changed nothing on the phone lately. I'll take another look tomorrow.
Some time ago I had to disable the pre-installed peel smart remote app on my note 4 because an update resulted in bad invasive behaviour. I would completely uninstall that app but that's Samsung's fault for not allowing that