My phone dials #3282 (#DATA) by itself. Which app did it?
In my case, the app was Nova Launcher.  I had recently enabled the permissions needed for gestures, and presumably, one of the defaults is to dial #DATA when a user swipes down on the screen.

To disable this gesture, start Nova Launcher, go to Settings, and edit the Swipe Down gesture (or whichever gesture is assigned) and choose None or another action.