Cover Block with parallax effect does not use responsive friendly srcset attribute

[NicoHood]

Description

I noticed that the Conver Block uses a css background image instead of a normal tag. The srcset cannot be applied to that, so it forces the client to download the original size image, which is bad.

Step-by-step reproduction instructions

1. Create a cover Block
2. Upload some large image
3. Enable parallax Effect

Screenshots, screen recording, code snippet

No response

Environment info

WordPress 5.8 with stable Gutenberg

Please confirm that you have searched existing issues in the repo.

Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

Yes

[NicoHood]

Another issue with the css background image is, that this does not support lazy loading!