Not an astronomer, but there's at least one important thing to consider:

Stars form in denser regions of gas. However once they grow large enough to start fusion, the solar wind will blow away the gas, halting growth of that star system. So stars have a kind of limit when it comes to size.

That's what makes these early universe large black holes problematic (read, exciting new science): we know black holes the mass of stars can form by a super nova. However the only way we know that these super massive black holes can form is by smaller black merging. There's simply not enough time for black holes as large as we think jwst has seen to form in the age of the universe we think we're looking at. Something in the physics has to give.