Would there be a moment we cannot zoom in further because we hit the event horizon with the jwst? Or are there still hidden galaxies behind what we can see with the jwst?
I think it won't be a hard border per se, but it'll just turn into extremely redshifted noise at some point; beyond infrared you end up in microwaves, which leads to the cosmic microwave background radiation: https://en.wikipedia.org/wiki/Cosmic_microwave_background
The furthest back potentially visible stuff before the dark age won’t be galaxies, which formed after the first stars. We still have never seen a first generation star, and I’d be surprised if Webb could.