Why the 360x640px resolution is currently the most used one?

Recently, after checking which is the currently most used resolution among all devices I was surprised to find out that we have a new leader - the 360x640px resolution.

This is obviously mobile resolution. However, after researching which devices operate at 360x640, there is not much of them. The majority of current mobile devices use 1280x720 or bigger. So:

What causes the surge of the 360x640 resolution?

Update: The mobile resolution has already significantly passed the desktop resolution as the most used one.