@mons 

This picture seems to have a background, although I used remove bg as always.

Could you check that via your tools, please?

Will do, but there doesn't seem to be anything wrong with it at all, at first glance.

I see what you mean now.

When you have a source image with its background removed already, I suggest putting it through remove.bg anyway to see if it smooths over any jagged edges that the previous cutting process left 🙂

@mons I'm not sure what happened with the version you uploaded, but it seems that by putting the image through remove.bg again it duplicated transparent pixels (maybe encoding messed up on the original, which is what P-Jo referenced with the thumbnail image having “ghosting” around the hair edges)

In addition to putting it through remove.bg, I used blur to soften the somewhat jagged edges. It had an index layer, which led to the effect you mention.

The edges on your cutout looked like this which I don't think are very good -  still noticeably jagged and a bit rough around his right ear - as well as having snow where the transparent pixels were duplicated. I found that just saving the image, opening it in Photoshop and exporting it again was enough to fix the problem P-Jo had.