Transparent Gaps between textures

Hello community!

I am currently working on a 2d terrain generator. Below you can see a 25 by 25 Chunk.

My chunk is made out of 2 Meshes. The first mesh is the big background. The second one is everything else.

I use a texture atlas and uv coordinates to give the mesh different textures.

But in the second picture you can see my problem.

Transparent lines between the textures whenever I move the camera. Can anyone imagine what the problem is?

Things I already tried to do:

1. Change max texture size above real texture size.

2. Change wrap mode to Clamp and Repeat

3. Texture Importsetting to Advanced. (Turned off Mipmapping, tried every single format type)

I really hope someone has a solution to this, as this is ruining complete the visuals of the game.