Galaxy 434625, marked with a square, as seen by Hubble how it looked 11 billion years ago. Star-formation was apparently different then. HST/NASA /ESA
The rate at which new stars are formed is one of the most important things astronomers can find out about distant galaxies, and it is well correlated with many other properties, like their mass. So, discovering that one of these correlations doesn’t work in the early universe is a big deal.