Samsung is apparently removing the option to unlock your bootloader from Galaxy devices with its One UI 8 update, at least in places where that was still available. For Galaxy owners in the US, ...
Samsung’s One UI 8 update reportedly removes the option to unlock the bootloader on many Galaxy devices. This change impacts advanced users who customize their phones with custom ROMs or root access.
Unlocking allows you to root a phone and make changes to the core software. Naturally, most device makers discourage this behavior, but Samsung's setup on the Fold3 is downright hostile to modders.