My take on it is that it's been known for a long time (1970s) that supermassive black holes couldn't possibly have been formed between the big bang and the present, never mind the early times that JWST can see into.
Astronomers will make excuses for that and say that they didn't really prove that galaxies had black holes in them and that they were really massive recently but the tension has existed for a long time because people suspected that galaxies had huge black holes but there was no path to form black holes that big.
I worked for arXiv in the 00's and had a coworker who'd gotten a PhD in astrophysics about accretion disks who was really bitter about how the poor job prospects in astronomy let senior astronomers bully junior astronomers creating a false consensus about how accretion disks and other phenomena worked. When I first heard about ΛCDM my first instinct was that some bullying was going on. [1]
Observations that the "first billion years" might have taken 10 billion years or so have been coming for a while but with JWST there is an absolute flood of them.
[1] The cold dark matter doesn't bug me half as much as the dark energy. I mean, once you look at anything bigger than a star cluster it's obvious that dark matter is there or otherwise gravity works differently in a way that is huge for objects bigger than a star cluster but doesn't show up in precision measurements at all in the solar system.