Back color of side of 3d object renders above of another 3d object

Hi. I am trying to to create big cube from 5 small cubes, but I noticed strange thing:
The side of an small cube what isn’t faced to directional light renders above second small cube front side:

image

view from another angle is ok:

image

but on some angles it also renders wrong:

image

it occurs in play mode too.

how can I fix this? Thanks.

Cocos Creator 3 preview.

@Horchynskyi Can you provide a demo that reproduces the problem?