Random vibration, ghost chattering – however you call it, if your phone switches off for no apparent reason, it's pretty frustrating. Finding the source of a phantom vibration can be almost impossible if there is no notification, especially considering the myriad of apps and system processes running on your Galaxy device.
With an app developed by Samsung called Nice Catch, however, you can do this now. Go to the root of what your Galaxy happens to vibrate. With this tweak enabled, you'll now be spared the headache of the Finagling with your device to test apps with the elaborate method of trial and error.
: Update to a User Interface (Android Pie)  First, note that Nice Catch only works for Android 9.0 Pie or higher, aka One UI. So, while you're at Oreo, you'll have to wait for the latest update to be available for your device. Check the link below to see when the phone will receive the update.
Step 2: Install Nice Catch
If you're using a UI, the rest of the process is simple. Next, open Galaxy Apps (you'll find them in your app drawer), then search for "Nice Catch" and tap the top result. Alternatively, tap the following link from your phone and then open it with Galaxy Apps when prompted. From there, tap the way you want to download the app.
Nice Catch is automatically enabled by default and immediately starts recording vibrations. That is, if you had a phantom vibration before installing Nice Catch it will not appear in the logs, but all future vibrations will be logged.
Still, to find out which apps or what system processes have recently caused your phone to vibrate. Just open Nice Catch and tap the words "Vibration History" (not the toggle switch next to them). The last week's vibration is shown here with timestamps and dates, and the apps that caused each vibration are clearly displayed. Therefore, it should be easy to find out which app causes the phantom vibrations of your Galaxy.
Here you can either uninstall the app that caused your phantom vibrations, or simply adjust the notification settings to disable vibration. Go to Settings -> Notifications, locate the app and select each option under "Categories". Then turn off the switch next to "Vibrate" on the following screen.