Vector Flat Design
Flat design is a minimalistic design, clean, open space, crisp edges, bright colors and two-dimensional illustrations.
Flat 2.0
Flat 2.0 provides an allowance for subtle details and does not “outlaw” techniques – shadows, gradients, layering – that were not a part of flat design.
This brings as a novelty to Flat Design the sense of depth.
Illustration by Hey from www.handsomefrank.com
Taking these two concepts as a basis, the type of image included in the question can be found in Google Search as Vector Flat Landscapes or Vector Flat Scenes
Flat 3.0
There is a Vector Flat 3.0 that keeps the same formal typology, trying to get away from the vectorial neat cleaning sensation with additions such as noise, grain, textures, spots, fog, scratches, splashes... and perspective. A vector photographic illustration. Some examples:
Michal Sawtyruk
Sam Ji
Matthew Lyons
Zak Steele-Eklund