When creating a new world, selecting "Hardcore" as your game mode, then going to More Options, the "Buffet" world type, choosing an option there and returning to the More Options screen, the buttons for "Allow Cheats" and "Bonus Chest" both appear to be clickable, and can be clicked, although the settings do not change. Minor visual bug.
This is a duplicate of MC-10209 and IIRC fixed in the 1.15 snapshots