Was it ever explained what Scar did to ruin everything? Like, was it overhunting, or mismanagement of resources? Like when Simba came back, everything was a wasteland. Then after overthrowing Scar it rained like once and everything was fine again.
I think the implication was that without the top predators controlling the hyena population, the ecosystem was out of balance. This is sort of a real ecological phenomenon called meso-predator release, and explains why predation on some herbivores actually declined when wolves were brought back to the western US, though it does not necessarily cause all the plants to die as depicted in the film—the harms are more complicated and nuanced.
However, I do want to say that the implications of this movie that the relationships between species are comparable to those between people is very incorrect and harmful. In fact if you ever rewatch this movie as an adult, some of the embedded ideology is very disturbing. Some authors have argued that the movie implicitly supports fascism, which I am forced to agree with.
some of the embedded ideology is very disturbing. Some authors have argued that the movie implicitly supports fascism
The 1994 version, or the 2019 remake? The original had the "Be Prepared" musical sequence where the hyenas are goose-stepping for Scar, clearing framing them as akin to Nazis parading for Hitler. I have not seen the 2019 version to know what may have changed.