Can you help me identify technical issues for these pictures. They were rejected.

Stock has very high visual & technical quality standards, regardless of what kind of camera you use.  Under the right conditions, phone cameras can produce good results.  But IMO it requires more effort, multiple exposures and experimenting with manual settings.  See links below.

https://toughnickel.com/self-employment/Create-Passive-Income-With-Stock-Photography-On-Your-Mobile-Phone

• https://helpx.adobe.com/stock/contributor/help/reasons-for-content-rejection.html
• https://helpx.adobe.com/stock/contributor/help/quality-and-technical-issues.html
• https://helpx.adobe.com/stock/contributor/user-guide.html/stock/contributor/help/photography-illustrations.ug.html
• https://helpx.adobe.com/stock/how-to/tips-stock-image-acceptance.html

In addition to being underexposed, particularly in the shadows, and not sharp enough, most of the images, the 2nd one in particular have a slightly blue cast. WB needs to be adjusted. Not sure whether you used any editing software, but I find that even the best of my iPhone 12 images need some slight tweaking in Light Room.

Hello, I'm sorry but, I do not think that the photos are sharp.