Invite your feedback on the photo of the painting done by me

It's a nice watercolor painting.  But the rough paper texture could pose problems for you. The texture could be flagged as image moiré. For this reason, I recommend using smooth, hot press paper for paintings that you plan to digitize.  Smooth paper produces better results on screen.

Also zoom in and crop out the borders.  Adobe Stock prefers images without frames or vignettes.

https://helpx.adobe.com/stock/contributor/help/editing-dos-and-dont.html

Hope that helps.