Transparent black gradient on pictures

Hello,
On the pictures of my articles, I systematically have a transparent black gradient. How and where can I delete it?

Thanks

Hello,

My website is not public

Please see a picture of the problem :

The black shadow is only on the top picture and at the bottom of the picture :
https://ibb.co/cTnZfjY
The image at the top of my article uses the featured image from the article.
The (good) original picture : https://ibb.co/191WFN0
A black filter is added to my template but I haven’t configured anything special

Please see the post setting in the article :
https://ibb.co/Rv6FxPg

Please see all the config of the post setting in the theme panel
https://ibb.co/xFRKYzG

Thanks for your help,

Thanks,

You are right.

Please see https://ibb.co/cFPN7jX

The picture has an overlay black color.

I don’t know how to remove it on all models

Thanks it works !