[postoplust]

> Hard Mode: Any revealed hints must be used in subsequent guesses

As implemented, hard mode doesn't count gray letters (letters nowhere in the solution) as hints. You're allowed to reuse gray letters, but true hard mode should prevent that.

[stavros]

Oh hmm, I've never thought of gray letters as hints, more like the absence of hints.

[nextaccountic]

Some wordle clones handle this correctly, like https://term.ooo (Portuguese language)