Hi Lyubomir,
If I get what you’re trying to do, you want to non-uniform scale the Noise. The Noise position input is looking for a 3 vector input (XYZ) and your ‘Tile of the Noise’ is only 2 vectors (XY). Your ‘Size of noise’ works because it uniform scales all 3 vectors. Here is how you can scale X Y Z independent of each other.
Hope I understood what you were trying to do and this helps.