It's a conflict with the rest of the spyware you have on your phone that causes Amethyst to behave in a buggy manner, crash a lot and use tons of battery. For me Amethyst runs super smoothly, never crashes, doesn't use a lot of battery; for others it's the opposite. The solution is to stop using phones.
Discussion
The solution is to stop using phones that violate user rights by preinstalling a bunch of unnecessary proprietary services. https://grapheneos.org
I have zero problems with Amethyst except the occasional slow loading times and scrolling issues.
I decide to use this phone, the battery can last at least a week :). 