"Alarmingly, every single one of the mites the researchers screened was resistant to amitraz, the only viable mite-specific pesticide—or miticide—of its kind left in humans’ arsenal."
This is to be expected, eventually evolution will produce a small amount of a species that is resistant to a chemical, then those will likely be hyper successful at breeding. Honeybees are not native to the Americas, it seems like we've imported a major feast for these mites. Perhaps there's another organism that preys on these mites. Nature often provides the a cure with the poison.
[0] - https://choosenatives.org/articles/native-bees-need-buzz/