Ok maybe i will take a look how to change it in blender. For now it’s not such a big problem, just not so nice to look at… I would guess the different file size also comes from, that blender only exports is at one mesh and the sandbox does like 8 meshes. Like one for each side, and the hole also has two.
Idk maybe i find out how to set blender to also export smoother and in 8 meshes, because i actually prefer/need them… but yeah babylon sandbox does even different weird things like inverting the coordinates because my gltf files are bad? But blender also fixes that somehow to be right again…