Rejected Photos

If they say quality issues, they just noticed quality issues before the IP problem. I feel Abambo has much good advice here.

Let me guess: quality issues! You should always tell us, what Adobe told you, why they did not accept the pictures.

Horse:

There are exposure issues:

• missing blacks
• missing whites
• underexposed shadows.

The histogram shows the missing blacks (left) and whites (right)

The asset also lacks contrast, but that is a direct consequence of the odd histogram.

In addition, you have applied a lot of noise reduction, making the horse look out of focus. It is well possible that you pointed the focus somewhere else than on the horse's eyes.

Hambourgers:

You have artefacts, due to the high ISO and noise reduction, but I can see still colour noise

.

I also see chromatic aberration. 

The logo and the tradename here is an IP violation.

The framing of the picture is terrible. The fat stains on the containers are disturbing. If you would like to do food photography, you should know that this is a highly choreographed art and no element in the picture is there by chance. Your picture is a snapshot of the kind I send to my friends, when we are messaging about what we eat. And even then, I choreograph the items in a way that people get hungry and want to join the meal.

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

What specific reason did Adobe give? I can see an IP violation in one (sweetener sachet).