Fair enough. Its utility is mainly for serving as a virtual microscope for conservation purposes. For example, here [1] is a lead soap [2] particle up close, here [3] is a very detailed view of the dog showing exposed canvas, and here [4] is some retouching from a past conservation treatment in the face of the main figure. These kinds of things help us to make decisions about future conservation treatments, help to document the exact state of the painting for future comparison, and help us to appreciate Rembrandt's mastery with paint (e.g. the unintuitive way he depicts lace [5]). All in all, it should give the public a greater appreciation of how much effort we put into collection care at a museum.
They work fine for me in FF 95.0.1 on Ubuntu, with adblock enabled (it's doing nothing on that page). Perhaps you have an extension that is not playing nice?
[1] https://hyper-resolution.org/view.html?pointer=0.326,0.666&r...
[2] https://www.metmuseum.org/about-the-met/conservation-and-sci...
[3] https://hyper-resolution.org/view.html?pointer=0.522,0.466&r...
[4] https://hyper-resolution.org/view.html?pointer=0.551,0.619&r...
[5] https://hyper-resolution.org/view.html?pointer=0.500,0.527&r...