What problem does this address?

We currently use the wp_getimagesize() function to determine an image's height and width when using external images in order to calculate CSS values for the lightbox. However, this creates unnecessary network requests and also breaks when external images are no longer present at the specified URL.

What is your proposed solution?

When using external images, we actually don't need to fetch the width and height data because the responsive image in the content is the largest image we have available, so we should be able to remove the call to wp_getimagesize() and revise the logic, and the lightbox should still work without issues.