Welcome aboard!
It’s a side-effect of the technic used: the vertices are pushed away from the surface in the direction of the normals to inflate it. If two faces sharing a vertex does not have the same normal at this vertex, there will be a gap between the faces at this vertex because the vertex is not pushed in the same direction for both faces.
The only fix I can see is to smooth the normals so that a vertex “shared” by multiple faces will have the same normal whatever the face it is in.