What’s wrong with this photo? Reason for rejection – quality issues. Can the upload process cause quality loss? When I look at the thumbnails after uploading, they really do appear blurry, even though the original photos are perfectly fine.

This post belongs in the Stock Contributors forum below.

https://community.adobe.com/stock-contributors-36

Thumbnails are just low-resolution previews. Reviewers evaluate full-sized images at 100-300% magnification.

To be accepted into Stock, your content’s visual & technical quality should meet or exceed what Stock is selling. This is what you’ll be competing with for sales

https://stock.adobe.com/search?k=sea+cliff

Read your Contributor User Guide for more about what’s required. 

• https://helpx.adobe.com/stock/contributor/submit-your-content/submit-photos/photo-submission-overview.html
• https://helpx.adobe.com/stock/contributor/submit-your-content/submit-photos/technical-legal-requirements-photo-submission.html
• https://helpx.adobe.com/stock/contributor/submit-your-content/submit-photos/photo-editing-best-practices.html

Hope that helps.

It looks fine when viewed as a whole, but if you zoom in to 100% to check it, you notice the poor image quality.
It was likely rejected because it has a texture resembling an oil painting.