@claudiu-marian, I can't tell what technique you're using for your cuts, but I strongly urge you to watch the below tutorials and start using remove.bg for your works, because these are otherwise not really good enough.

It's a fantastic free online tool which does the heavy lifting for you by removing the background in the source image, leaving you to only rotate, crop and/or nudge the collar upwards. It's tremendously easy to use and provides fantastic quality. With it, you can go from source to cut in a couple of minutes for the vast majority of images.

Here's a couple of videos on how to use it, one when combined with Photoshop and another using photopea.com, which is a free online app so close to Photoshop that it has the same shortcuts, layout and icons 😉 If you don't have Photoshop, photopea.com is the tool I would recommend to use to tweak the draft cut produced by remove.bg. It's more powerful and versatile than GIMP and other similar tools.

Also, we ask for all cuts to contain a collar within no more than 2-3 pixels of the chin, and for them to be cropped no more than 2-3 pixels above the head.

If the source image contains a collar which is lower down than that, use the below technique:

Also, if you have multiple images to upload, please do so as a pack, rather than individually 👍