Needing critique with my files

[Newbie Gem]

I'm very new to PNG files and I submitted my first 3 png files that got rejected later on . the cause is Quality Issues , I already know these have a high chance of being rejected  to this png thingy but still submitted it because I kinda wanted to experiment with it

[Abambo]

Butterfly: artefacts a little bit everywhere and errors with the cutout.

With a clean cutout, you would have a clean, thin red line around your butterfly.

a) Elements that should not be transparent are transparent (cloud of red dots)

b) Your contours are not clean.

If you submit such en asset, as soon as the buyer want's to put this on a background, you will experience artefacts.

Fox 11:  you need to correct this soft look (a) and clean-up the artefacts (b).

The cutout is better than with the butterfly, but still not good enough.

fox 2: Soft look, some compression artefacts and plenty of cutout errors.

(I've changed the line colour to green)