The problem with responsive images in Sp Page Builder has always been the width and height attributes and the wrong way they entered those options but for CSS (google does not accept). I always asked for it to be done correctly and I thought they never listened to me.
Today for work I had to review the code for the media type field and I found references to width and height, so I decided to print the object on the screen which returned objects, some had width and height properties and some did not.
Then, while testing, I found that the images selected with the "Choose Image" or "Replace" buttons do not have the width and height properties, but if you write the path of the image in the field it does have those properties, so I think there is a bug.
I must congratulate you for adding that feature and also ask you to fix the bug.
Tested on: PHP 8.2.5, Mysql 8.0.18, WampServer, Windows, Firefox and Chrome latest versions, SPPB Frontend Editor.
Regards