Embedding transparent BG images into screens

I am trying to embed an avatar image into a screen I am designing in Google Stitch. Although I tried multiple image file formats (JPG, PNG), a few ways to explicitly make the image with transparent background (with explicit guidelines to AI Studio and with an external BG remover script) and I mentioned the requirement of transparent background embedding within Google Stitch prompt, I am keep getting a checkers backgrodung around the embedded avatar.

How can I fix it in stitch?