@Alieeks May I ask what method you use to remove the background from the source image? 

Most of these have some leftovers around the head, as well as a white outline around the hair (snow) which can easily be cleaned by putting the image through remove.bg

I'd recommend watching this video and when you make a cut just copy the steps that are done there 👍

Straight out of Panathinaikos's website. These were already png's.

If the source has a transparent background please still check for snow using a dark layer, most of the time there will still be leftovers like here