Facets of polygons on a global view of the planet

What could this problem be related to? Incorrect lighting or low number of sphere polygons?

That’s usually caused by the atmosphere shape not matching the globe shape. Unreal’s atmosphere is (unfortunately) a sphere, while Earth is not. The CesiumSunSky component attempts to automatically account for this by changing the atmosphere size based on camera position. If you’re using Unreal’s SunSky instead, switching to Cesium’s should fix it. If you’re already using CesiumSunSky, then the atmosphere is most likely being adjusted based on the position of the “wrong” camera. In the Editor, it uses the first editor viewport to scale the atmosphere. In-game, it uses the first player pawn.

Thank you Kevin, you were right. I was able to fix it.