What problem does this address?

While creating a design for Twenty Twenty-Three, I noticed it's not possible to add a gradient overlay to the featured images of posts, as the Post Featured Image block is used, where this feature is not available. It would be possible with using a Cover block, which can also display the featured image; however it's not intended to change the markup of Twenty Twenty-Three.

What is your proposed solution?

To enhance the Post Featured Image block, the overlay feature from the Cover block should be made available. This would enable more design possibilities using this block, without having to rely on the Cover block instead.