Collider2D's Edge Inaccuracies

I’ve been working on a couple of project and i still can’t make them work right.
Every time i use polygon collider 2D there is a poblem with it’s border. i placed every point myself and i thought collision would be as accurate as i made it, but all egdes for some reason are offset a little outside.

For example i made a stack of small objects (pixels per unit is 16 and the scale is 1)

But as soon as i start the game all of them push each other away making tiny gaps

Can anyone explain what is going on and is there anything i can do to prevent this?

There’s nothing inaccurate about it, it’s not a pixel-based physics system.

There’s a contact offset around polygons/edges for collision stability as defined in Physics2D.DefaultContactOffset.