Change zoom-behaviour of WooCommerce-lightbox / PhotoSwipe

On the website, which I’m developing, WooCommerce is used to sell high-resolution airport images and PDF-files. Please find an example product page here.

If you click the product image, you will see that a Lightbox opens up. I’ve determined this to be PhotoSwipe, documented here. The lightbox should show the image in the format large (950 pixels long side) and whereas that image is served (this file, to be exact), a CSS-scale-function is applied such that the image is shown to the user at 650px, as shown on the picture below (2560px wide monitor). In the HTML, this is applied as an (inline) CSS-transform:

transform: translate3d(952px, 168px, 0px) scale(0.671979); 

enter image description here

This way, it offers no real benefit over the preview that is shown on the product page itself.

My questions:

  1. Why does WooCommerce/Photoswipe behave this way? Might it have something to do with DPI and high-resolution monitors?
  2. How can I change this behaviour?

Additional information

The website is running a custom (child) theme, based on Leto.

In attempting to solve this, I’ve tried multiple things. If I remove the code prescribing the use of the large image size (currently achieved using the code below), the full image size is shown (1000px wide). This is also scaled down, but to a lesser exent. However, as the shop is precisely selling high-resolution images (from 1200px onwards), we prefer to limit the size of the images served in previews (even though these are watermarked).

add_filter( 'woocommerce_gallery_full_size', function( $  size ) {     return 'large'; } ); 

I’ve also tried to disable PhotoSwipe completely, using the code below. That is effective, but obviously removes the lightbox functionality. Especially the fact that visitors would then have to use the ‘previous’/’back’-button in the browser to navigate back to the product page is undesired. However, I am open to suggestions for another lightbox-solution than PhotoSwipe.

add_filter( 'woocommerce_single_product_photoswipe_enabled', function(){     return false; }); 

A number of other changes related to images and image sizes have been applied, but do not seem to affect the problem:

  • medium_large size has been removed
  • srcsets are limited to show at most the medium size