Apple has threatened to remove Amphetamine from the App Store

I mean, on this point I'm actually inclined to think Apple's general policy is reasonable, even if it sucks that Apple is only now adding or enforcing this rule.

It doesn't want apps that jokingly call themselves "Crack Cocaine", "Crystal Meth", or "Mango Vape". It doesn't have anything to do with them actually promoting drug use, but it helps normalize illegal drug use in a way, while Apple wants to keep a "family friendly" approach to its App Store.

Honestly, if I were the creator I'd just rebrand it.

I remember coming across the app years ago, it wasn't obvious from the name what it did, and when I finally understood it, it just seemed like the creator was trying a little too hard to be "edgy". And if you want the widest possible usage/distribution of your app, "edgy" is usually not the way to go.

No. Amphetamine is the name of a chemical with both legal medicinal and illegal applications. I might agree with you if the app's name was "Meth" or some other slang term for a stimulant drug associated with illegal use.

Another comment in this thread said the same thing, and someone replied saying "but I take meth to function (desoxyn)".

The quote was "I use methamphetamine (desoxyn) to function!"