One area I find DRY particularly annoying is when people overly abstract Typescript types. Instead of a plain interface with a few properties, you end up with a bunch of mushed together props like { thing: boolean } & Pick<MyOtherObj, 'bar' | 'baz'} & Omit<BaseObj, 'stuff'> instead of a few duplicated but easily readable interfaces:

interface MyProps { thing: boolean; bar: string; baz: string; stuff: string; }