store images from a lightbox in the database

You might need to simply pass the data from the lightbox back to the page.

How do I pass data between a page and a lightbox?
When you open a lightbox using the openLightbox() function, you can pass an object containing data to be used in the lightbox. In the lightbox’s code, you call the getContext() function to retrieve the data sent by the openLightbox() function.

When you close the lightbox using the close() function, you can pass an object containing data to be used by the page that opened the lightbox. This data is retrieved from the resolution of the Promise returned by the openLightbox() function.

https://www.wix.com/corvid/reference/wix-window.lightbox.html