I’ve also seen them behave very weirdly and inconsistently. There have been cases when I’ve had to explicitly declare that a value has an enum type, even though its type is already one of the enum’s values (and not a literal of the same value, but literally straight from the enum itself).

From what I can tell, they were an early addition from back before TS had unions, and it feels like they live in their own world within the type system. I would go further than saying you should disallow them with a linter, and say that they should be deprecated in the language. Right now they’re just a foot gun for new TS devs.