In many cities around the world, Google Maps shows a 3D view of all buildings around to help you navigate and figure out what places look like without having to individually open each listing to check photos. The feature is nearly as old as Maps itself on Android, but until now, you were stuck with this rendering and couldn't turn it off. A new layer lets you toggle 3D off to enjoy a flattened map.
The layer button is showing up on Maps v10.28 and above. You'll find it in the layer pop-up, right next to another recent addition, Street View. Turning it on shows all 3D buildings and constructions, turning it off smoothens the map. The latter should hopefully reduce strain and speed up things on smartphones with limited resources or with a slow connection. It can also be useful if you don't enjoy looking at a busy map.
The toggle works in the regular, top-down Maps point-of-view (animation at the top of the post) as well as the sideways view (animation below), which is accessible by swiping up with two fingers. Also keep in mind that the 3D structures only show up with the Default map type, so if you're browsing in Satellite or Terrain mode, you'll be switched back to Default before buildings appear.