Following #5247
I think, introduced in 30979ed

Prettier 1.16.0
Playground link

--parser typescript

Input:

const foo = (): (() => void) => (): void => null;
const bar = (): () => void => (): void => null;

Output:

const foo = (): () => void => (): void => null;
const bar = (): (() => void) => (): void => null;

Expected behavior:
A choice between (): () => void => (): void => null; and (): (() => void) => (): void => null;.
I think the second one is better.