Moral norms evolve to ensure survival of it's bearers.
Basically under no circumstances it will be immoral for the population at large to have kids because such moral norms will quickly cease to exist. Eather because it's bearers cease to exist or more likely because they move on to more suitable moral norms.
I say "more likely" because humans obviously didn't get extinct despite bringing kids into the world of suffering for about a million years.
I was literally told as a kid that we were heading to overpopulation and that having kids would be immoral. The Chinese committed a genocide against girl infants with that as a justification.
I'm not saying that's something that can't happen, I'm saying it can't last for long.
The "immoral to have kids" crowd still exists e.g in Europe but their options are to either change their mind or to be gradually overrun by people who think otherwise.
Basically under no circumstances it will be immoral for the population at large to have kids because such moral norms will quickly cease to exist. Eather because it's bearers cease to exist or more likely because they move on to more suitable moral norms.
I say "more likely" because humans obviously didn't get extinct despite bringing kids into the world of suffering for about a million years.