How to prevent flickering on mesh boundaries?

Question

I am generating my levels through GDScript by placing cube meshes next to each other. (Can't use GridMap for other reasons which I can explain if needed).

var tile = cube.instance()
add_child(tile)
tile.global_translate(Vector3(x, 0, z))

They are all on the same Y plane, but different X/Z positions.

Unfortunately, playing through the level using a standard camera, there is flickering on the surfaces of the meshes. Here's a video:

Some screenshots detailing the problem:

These lines usually appear for half a second and then go away, but creates a very jarring visual experience.

How can I fix this? Thanks for your help!

Comments

The issue is much more apparent with a DirectionalLight (I cannot reproduce it with no DirectionalLight and only ambient lighting). It appears regardless of whether the meshes are shaded or not.

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Issue still occurs on 3.1beta