Problem: Clicking "Unlock All" discovers and unlocks everything that currently exists, then disables the button. Things that are added later are not unlocked, and cannot be unlocked due to the button being gone.
Solution: If anything exists which isn't discovered and unlocked, the button comes back.
Requires Lovely. Steamodded is optional, but allows unlocking items on a per-mod basis in re:Unlock's config tab. (It is definitely possible to not rely on smods for that but I don't know how to do UI 👍️)