quality problems

4th:

• Inconstancies in the background:
  
• Other artefacts.

5th:

• Chromatic noise
  
• @daniellei4510 mentioned the hand.

6th:

• Colour clipping
  

• not very sharp
• compression artefacts

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

For Dynamic-Digital-Masterpiece.jpg, their left hand is drawing with their right hand.