The issue seems related to the Lightbox Addon collecting images that are present in the DOM but not part of the current project content.

On a direct load of a project page:

• the body tag is correct and shows data-type="project" and the correct project data-id
• the visible project images are correct
• the clicked project image has the correct data-id, for example data-id="97"
• however, the opened lightbox image has a different data-id, for example data-id="1081", and belongs to the static front page/news page

I searched the DOM and found that the wrong frontpage/news images are present inside the project page DOM, although they are not visible on the page.

They appear inside rows with classes like:

absolute-positioning-vertically-in-apl

The image column has attributes like:

data-type="img"
data-yvel="1"

The lightbox then opens a Swiper gallery with the frontpage/news images, for example 1 / 12.

Important detail:
If I temporarily disable the static front page in Settings → Reading, direct project page loads open the correct project images in the lightbox. When I set /news as the static front page again, the issue returns.

So it looks like the Lightbox Addon may be collecting hidden APL/frontpage images from the DOM on direct project page load, instead of only collecting images from the current project content.

This happens even though the frontpage/news page itself does not have Lightbox enabled.