This is 'as designed'.
In real life, the hole will also deform a bit.
If you don't want this, you should make the hole in the beded part.
thanks for the reply,
Yes, I thought about that, but from the other hand after creating a hole on the rounded surface I need to redraw this hole on the flat.
I wish I had at least a centreline ...
what also is no problem, since You have an option when creating the flat pattern, to keep holes as cylindars.
So You can create the hole on the bended surface AND also will have a cylindrical hole on the flat pattern.
This also should allow You to align those holes with other axis