In Posts, when no Featured Image is selected by the Editor, the 1st image appearing in the Post (if there is one) should be used and displayed in Search results and the Articles block.

As an Editor
I want the Featured Image to be the same as the 1st image in my Post
so I do not have to attach an image to the Post twice.

As an Editor
I want to override the default Featured Image
so I am able to chose a different photo than the 1st one that appears in the Post.

FYI, aradu ltiralon

Please investigate why core functionality broke because this was supposed to be working before

Behaviour when there is no image will stay the same as its currently working - Nothing will be shown