https://www.vice.com/en_us/article/z3mxxa/ancient-galaxies-are-a-stress-test-for-established-physics-study-says

The view of the ancient universe revealed by the James Webb Space Telescope (JWST), the most powerful observatory ever launched, is so unexpected that scientists think it might pose a fundamental challenge to our basic understanding of the cosmos, reports a new study. 

The telescope has glimpsed inexplicably massive galaxies that formed some 500 to 700 million years after the Big Bang, leaving researchers baffled about how such galactic behemoths managed to emerge so early in cosmic history. The existence of these galaxies may present a serious challenge to the standard model of cosmology, also known as the Lambda cold dark matter (ΛCDM) model, which is an extremely well-corroborated framework that accurately predicts many phenomena in the universe.