I am trying to paste a PNG (I also tried several vector formats) on an PNG (I also tried SVG). I am pasting a transparent + black Layer (which I created by filling a selection with black).
When I import the layer - it comes out green…!)
Why is this?!?
Might your foreground color be green?
Your flag image is in colour indexed mode and the colour map does not contain black.
When an image is pasted into another, the pasted-in image takes the characteristics of the base image. This works both ways indexed <> RGB
Change the flag image to RGB Image → Mode → RGB and try again.