Why do decals stretch on a model from Blender in the Unity engine?

Question

Unity

Good evening!
I ran into the same problem and haven't found a solution on the web yet. I make a model in Blender for an FPS shooter, often starting with a cube and stretching it in different directions (for example, the wall of a building). Next, I export the finished model to the Unity engine as a Blend. or FBX file. I assign Mesh Collider to the model parts (without changing the settings). Next, I launch the game in the editor and take a shot at the model. Decals are displayed on the model, but they are stretched. Decal stretching does not occur when shooting at terrain, or at a part of the model that has been minimally stretched in Blender. Those. There is a relationship between stretching a mesh in Blender and stretching decals in Unity. But I can't figure out how to get the decals to display correctly. At the same time, horizontally placed meshes do not distort the hit decals at all or almost, although they can be stretched.
Blender version 2.8
Unity version 2019.1.9f1 I am attaching
an image and asking for help in solving the problem.