Which aspect of the answer do you want? You can write a textbook on such a broad question; how we determine the mass of a galaxy, its composition, its distance, etc.

JWST is seeing brand new things; globular clusters are so well documented as to be part of the original Messier catalog that predates the United States.

The answer is not rocket science. JWST saw something, scientists made an interpretation, there should be an explanation "why" somewhere. And you won't need to write a textbook on that because you can cite prior work.

There is no solid/proven explanation right now. Only hypotheses to be tested. It’s a new phenomenon they’re working to understand.