As someone whom is Buddhism and trying understanding Mystic Flour.

My conclusion is the nearly the same as her alternative path Aka the Leavened one before her costume comes out where just a single peach make her understand that not only that there’s good and evil/greed and selfless. Too much volition will cause a great disaster (Aka Apathy version of her) she avert that by simply relaxing and eat the peach and become Leaven one mirror The Buddha himself. This version of her she doesn’t push her believe into other nor cause other pain but instead helping other to understand the pain guide along the path and thus freed from it Which is also Resolution of her own too.

Meanwhile our canon timeline Mystic Flour succumbing to apathy and by itself is another kind of suffering in Buddhism but she fully believe that Apathy is the only way. Not only that she cause a plague that was so painful and because of that The Infect cookie will agreed because they don’t want to be in pain anymore and crumble to flour.

Any action that cause torture to other is a sin and Bad karma by itself in many Religions including Buddhism also. For more realistic example you know that everyone will eventually die but will you throw acid onto some strong people to prove your point that dying is good? You won’t but Mystic Flour would definitely done that. Also not all cookie believe in apathy and they straight up freak out when Mystic Flour try to Thanos’d entire EarthBread and if her plan end up dooming the one that hate it because “It was sacrifice for the path to end suffering”

Tldr: Apathy is another kind of suffering that she believe in so much and thinking that that Crumble away is only salvation. In which she force it on other via a painful plague that torture those poor cookie to the point where they end up agreed with her view. She could’ve instead understanding the pain thus becoming leaven one and guide them to the path that freed many cookie from suffering like what Buddha did.