My silhouette PNG getting rejected for quality issues .

If you are using PS, within the layers, you can paint in the black halo. 
You have the selection. Make sure your selection is active. On a separate layer use your black paint brush to go around the edges. Make sure the colour is the same as your image and you are using a hard brush. 

Cheers

Nate

You will need a computer & professional grade tools like desktop Photoshop or Illustrator to create commercial quality artwork for Stock. Consumer level mobile apps might be OK for social media posts, but they can’t give you the detail and precise control that’s required for Stock artwork.

Also, you’re competing with an inventory of 45 million silhouettes, mostly math-based vector graphics.

https://stock.adobe.com/search?k=silhouette

Unlike pixel-based PNGs that get fuzzy when resized, vector based AI/EPS hold their sharp, crisp edges at any size on any surface. 

Hope that helps.

If you’re using Photoshop Express, it lacks the tools necessary to make the kind of edits these images require to remove the haloing.

I’m not sure which app you’re using, but why not ask about how to use it in the product community?

When you change the background in Photoshop, you can see that edges remain.
Also, the coloring appears to be uneven.