The same effect can be used to estimate cloud heights, and to identify aircraft flying above clouds.

Parallax based Cloud Detection for Sentinel-2 Analysis Ready Data Generation https://www.researchgate.net/publication/332999809_Parallax_...

Aircraft Detection above Clouds by Sentinel-2 MSI Parallax https://www.mdpi.com/2072-4292/13/15/3016

Is this at all analogous to how we used red/blue shift to determine the speed at which astronomical objects are moving towards/away from us?

No, that’s the Doppler effect. This is a time delay between when different colors were captured.

Ah gotcha. Makes sense. Thanks!

This is incredibly cool. What's the application (if it's possible to obscure whatever details you don't want to divulge)?

Its coastal physics work, you can infer near shore conditions by watching wave propagation.

So... like where submarines are based on water disturbances?

That's not what I'm doing but it seems possible you could watch refraction patterns and tell that there are submerged objects, but you'd need to know the water depth without that object there, as there'd be no great way to tell if the object is a submarine or a pile of sand. Also, most of these satellites pass over fairly rarely so wouldn't be super useful for tracking things that move. I'm mostly interested in finding the piles of sand :)