A good front-end developer knows how to architecture code for creating user interfaces, has a sense of design, is aware of UX, is sympathetic to accessibility, understands how the browser interprets CSS, is knowledgeable about the browser's rendering pipeline, knows the typical performance of API calls anywhere in the front-end stack, gets the division of responsibility between front-end and back-end.

Any job posting asking for proficiency in Yarn or SASS or React or whatnot is for expert monkeys who will produce web trash.