The error is caused because rpi-update is trying to copy the HardFP VideoCore libraries (/opt/vc/lib) but the expected files aren’t present in the firmware tree for the version you’re updating to (rpi-6.12.y). This doesn’t necessarily mean the update failed entirely, but it can cause issues with GPU-related libraries, such as:
Display output
VideoCore camera functions
DSI display functionality
This is particularly important if you’re debugging DSI display startup issues (e.g. blank screen / timeout errors), which may involve GPU/firmware components.