Im not very experienced with adobe stock.
But if i had to take a guess i would say its a combination of two things.
1. There doesnt seem to be a clear subject in the picture. Is it the pink rose? is the the yellow flowers?
2. 80% of the picture is out of focus. The focus on the yellow flowers is to soft.
Always mention the rejection reason that Adobe did give you. That helps for identifying the flaws the moderator saw.
I'm missing a focus point, even the pink flower is not exactly in focus, but it's the sharpest. From a composing point of view, the pink flower can't be the main subject because it's at the lower right border.
If you are new to stock, you should consider these resources: https://helpx.adobe.com/stock/contributor/tutorials.html
Please read the contributor user manual for more information on Adobe stock contributions: https://helpx.adobe.com/stock/contributor/user-guide.html
See here for rejection reasons: https://helpx.adobe.com/stock/contributor/help/reasons-for-content-rejection.html
and especially quality and technical issues: https://helpx.adobe.com/stock/contributor/help/quality-and-technical-issues.html
Thanks, Abambo for your comments and the resources shared: very useful! To mention the rejection reason is as follows: "Thanks for giving us the chance to consider your image. Unfortunately, during our review we found that it contains one or more technical issues, so we can't accept it into our collection."
Soft focus, Blown highlights, chromatic aberration, lack of contrast