does anyone maybe know why this gives an

[steel lichen]

dont know if you figured this out already but you're texture has 3 channels (R,G,B) but the texture coordinate is a vec 2 for your X and Y (or R,G as the material sees it) so you aren't able to do an add because theres a mismatch of channels.

You could either add a component mask between your multiply and add and mask it to 2 channels (R,G) or you can add a "Make Float 3" node between the texture coord and the add. In that case you could just set your B value to 0