The "UPD" is not just a minor bug fix. Based on changelogs from various distribution channels, the V12 update brings several disruptive features:
For users with devices that have not yet received the official update but support Project Treble, the can be installed using advanced tools. This is often referred to as the "Android Installer" approach in enthusiast forums. Prerequisites for GSI/Custom Installation Android Installer V12 UPD
Used to flash individual system partitions, unlock bootloaders, and install custom recoveries when the device is in bootloader mode. 2. Official Manufacturer Flashing Software The "UPD" is not just a minor bug fix