Here is a simpler explanation;

The further away something is, the faster it appears to be receding. The assumption was this slowed down at a constant rate over time. What Perlmutter et al discovered is that it drops off rapidly, then settles into a more stable rate of decline. The problem this created is the only driving force was assumed to be the Big Bang, yet instead it was like the universe had been shot out of a cannon, but after it slowed, a rocket motor kicked in, aka, Dark Energy.

Now if cosmic redshift were actually an optical effect, compounding on itself, this curve would be a very normal multiplier effect, that would eventually go parabolic. Yet that option is heresy and cannot be discussed.

Although, in 9 days, the James Webb will start sending in new data and if/when it starts finding heavier elements in those very distant galaxies, currently assumed to be young and mostly hydrogen and helium, as well as ever further galaxies and not primordial haze, it will be difficult to shoehorn it into the current model. Though I'm sure efforts will be made and patches applied.

Dark Matter, Dark Energy, maybe Dark Space....