Outline of a selection

[rich2005]

(05-19-2023, 01:15 PM)prandus Wrote: I will be more specific (English is not my language):
My end goal is to blur the background of a photo.
Online solutions are very good at cutting out a foreground.
So I got my foreground and wanted to stick it on the previously blurred image. The problem is that the colors of the foreground are integrated into the blurring and therefore bleed on the background (This effect is also visible on online solutions that promise a blurring of the background).

I am still not sure about the problem ?  Your attached image - what is it ? 

Looks like the on-line foreground extract has cropped the image

Try:

Invert the selection: Select -> Invert then Edit -> Cut to remove the semi-transparent pixels
Turn the selection off Select -> None
Make the layer same size as the background layer: Layer -> Layer to Image Size.

Otherwise, give a screenshot of the whole image not just a corner.