cette photo a été rejetée avec le motif générique : problèmes de qualité . pourquoi adobe ne donne pas la raison précise du rejet ?

I could not see any camera data, why? It suggests you did something that went to far enlarging the photo. If you use Adobe Photoshop and go under View to Actual Size,

you will see the photo too pixelated, which is possibly the reason for the rejection.

Also, keep in mind that sometimes a moderator will reject an image for quality reasons, then after making some adjustments and resubmission they will rejected for intellectual property violation. While family seals aren’t copyright, seal can have Trademark protection, and it is possible that could also be a problem. If that happens try removing the R F

Good Luck!   

The moderators review thousands of images per day. If they spent time explaining why each image was rejected, the review times would slow to a crawl. And some are already complaining of long review times. In addition, there isn’t always just one reason for a refusal. There can be multiple reasons and explaining each one would be too time consuming. That is what this forum is for.

The photo’s shadows are under exposed. Also, the photo is poorly cropped with space on the top, left, and right but the bottom is cut off. You should have cropped vertically. 
Furthermore, this might result in an IP refusal. The gate is someone’s property and design and is also the main subject of your photo.