## What problem does this address? <!-- Please describe if this feature or enhancement is related to a current problem or pain point. For example, "I'm always frustrated when ..." or "It is currently difficult to ...". --> The full screen icon was recently updated in https://github.com/WordPress/gutenberg/pull/55021, but the lightbox does not use it. ## What is your proposed solution? <!-- Please outline the feature or enhancement that you want and how it addresses any problem identified above. --> Revise the code for the full screen button, introduced in https://github.com/WordPress/gutenberg/pull/55212, to use the new icon.