My rule is that a functions' input and output should always be typed, even if it can be guessed. This to avoid mistakes when you refactor that function.
And to type anything that the compiler can't guess, like getElementById or JSON.parse. Often type it to unknown and write type guards. Anything else shouldn't be typed. You should never need to type already known types to unknown and back to a different type. You should never need to type to any except as a temporary fix for old code.
We're a place where coders share, stay up-to-date and grow their careers.
We strive for transparency and don't collect excess data.