It's just a package. It's not automatic nor hidden. If you've never noticed it being updated, then you probably haven't been paying enough attention to the package list when you did choose to issue a system-wide upgrade command.
Worth noting that BIOS updates frequently ship with ucode updates that are applied at boot before UEFI executes the operating system. So if GP is diligent about keeping the BIOS up to date, it's conceivable that Linux's ucode update has never had any work to do. At the very least this seems to be the case with Thinkpads.
