iPhone 6s 3D touch overly sensitive

On an iPhone 6s running iOS 11.2.5, suddenly 3D Touch is triggered at the slightest touch. For example, swiping to go back always opens the 3D touch app switcher and holding an app icon on the home screen opens its 3D touch shortcuts menu. Resetting the phone’s settings doesn’t help. What else could I try?

Go to Settings -> General ->Accessibility -> 3D Touch.

You'll see a slider there that allows you to control the sensitivity.

As described above, resetting all iOS preferences didn't solve the problem. However, finally, a full clean install (configure iOS 11.2.5 as a new iPhone) did