Weird artefact after deleting vertices and scaling model in blender

Armory Engine General
1

basic_wall_test.blend (666.3 KB)

town-hall2
town-hall2.jpg1024×1024 24 KB

screenshot1
screenshot1.jpg1922×1091 217 KB

screenshot2
screenshot2.jpg1922×1091 90.6 KB

I’ve been tweaking a model in blender, then when I compile the project I have weird artifacts showing in the windows??
See the files