Does not scale occasionally

Hello

I encounter this problem more often with chrome and less frequent with firefox. But on both browsers it happens occasionally and not permanent.
It is hard to see, the background images in this situation are ~1600 px wide. But on my laptop of 1280 wide sometimes the center of the image (a person) is peeking out on the right side of my content while normally there should only be the outside of the image.

https://www.onzesjaal.nl/

I cannot find any related error in the console..

Any ideas someone?
Kind regards

Edit: I made a testpage to demonstrate with a small image so you can see it:
https://www.onzesjaal.nl/test/

Edit 2:
The test page with the small image does not seem to scale at all, permanent. Sometimes it centers, sometimes it doesn’t..