Automatically changing the orthographic mode – perspective mode in Blender 2.8

In the new Blender 2.80 in the “3D View” window (3D Viewport), when scrolling a wheel to zoom or pressing the num pad buttons (1, 3, 7, 9) to center the view to different sides, the projection mode automatically changes between orthographic and perspective.

To disable this automatic mode changing, in the “User Preferences” window – “Interface settings”, change the value of the Auto Perspective checkbox: