Some phones require extra firmware to get good quality out of the camera that are protected with keys that get wiped when unlocking the bootloader, which is probably what was meant.
samsung apparently also used to have a kill switch on their S22s with the Exynos cpus in EU (the only models that are unlockable...Snapdragons are not). i have a hard time believing this tho if they permitted unlocking at all. most likely it was some signed firmware snafu as you say.
