Source for what? That sentence was a giant metaphor. Lot of things I was trying to say there could need sources. Do you mean nature naturally culling off oversized populations? Thats pretty general, although I can try by using my example of pathogens.
www.ncbi.nlm.nih.gov
This is a source that shows the relation between population density and the spread of covid 19. The lower the population density, the lower the rate of infection. Lower the rate of infection, less likely to become a pandemic. That is one way populations are naturally culled when they start to become to dense.
This is, in the context of humans, one of the only ways this happens right now. However, with other creatures, they may end up using up their resources, or the predator population will increase as it has more food. The viruses are like our predator, more people, more food, quicker spread
bio.libretexts.org
I know some people here dont believe humans cause climate change, but it wouldnt be the first time a life form changed the atmosphere and killed itself off. I doubt that we will kill ourselves off, but the point is - its natural and "nature" that "punishes" us. If we push our ecosystem out of balance, "mother nature" will "cull" us because the damaged environment makes it harder to live.
To explain the last part of the metaphor, it takes quite a few more words than "mother natures will get us good when she gets us":
Our issue is, all we do is keep putting a band aid on issues. What happens when it stops working? Think superbugs. We tried to fight off deadly infections, now those deadly infections are coming back full force, but we have less immunity because we raised our hygiene standards to prevent even mild infections of these bacterium in the first place. We get people to live to 100, they sometimes get dementia. We try to fight forest fires, and we make forests more flammable and forest fires more common. Fighting nature more means we have to fight nature even more, even if we can handle it for a while we may not get so lucky one day.