In human history, when there has been a period of protracted degrowth something bad has very much happened - usually civilizational collapse or severe prolonged economic downturn.
> We don't need infinite economic growth, infinite population growth, or even continued quality of life growth
I agree on the first two, but I believe that an expectation of the third is foundational to the post-Enlightenment social order. It has waxed and waned, and there have obviously been incredibly dark periods, but we've usually returned to "things will be better in the future" as a setpoint.
I read "Degrowth" by Kohei Saito recently. I found it challenging (in that it challenged a lot of my preconceived notions), but also a fairly positive approach to implementing degrowth. Sadly, at least in the US, I think it is alien to the American mind and only has a hope of being implemented at the local level in sporadic places.