From g.co/reportbadreflow

A third party JS widget is impacted by Scroll anchoring.
They confirm that overflow-anchor solves the issue but it means that they would need to reach back to everyone using the widget.


Example page: https://www.prettyyoulondon.co.uk/gallery

The JS widget is used to show photos.

"If you scroll to the bottom of the page, you can see that the photos of our widget continuously load and load over themselves instead of increasing the size of their container and adding themselves on. Adding "overflow-anchor: none" to the parent container solves this issue."