Weird physic effect if object collides in collider intersection

Hi,

I have a continously bouncing ball with an attached CircleCollider2d. It is accelerated by an positive velocity but as soon as it collides between two ground objects it seems like it does not hit the top of the ground's collider. Instead, it somehow hits the side and therefore it gets accelerated into the other direction.

EDIT:

The different ground tiles do share the same Y value so their should not be any edge between them.