I have a cube, made a loop cut, deleted one half and added a mirror modifier.
Then I wanted more vertices at the side so I could give the object a nice shape with proporetional edit.
I selected the two edges on the left side and hit “subdivide” for a few times. That gave me more vertices along the edges. BUT if was to grab the middle vertices and pull them to the side, it gives me distorted mesh as if not all vertices are connected to the edge. I do not know why this happens