1. normally: in the related posts below the single post, the featured image of the related posts is displayed.
2. as is: my posts don’t have a featured image (due to the migration) thus the related posts have no image at all, that is not okay
3. solution: provide the possibility to use the first image in the post itself to display in the related posts below the single post
4. result: the related posts will have an image
See the first image in the post (smartphone); below thos single post, you see the related posts without image because these posts have no featured image
The picture with the smartphone should appear on the left