On my T480s the mic mute button is handled in hardware/low-level firmware however all it does is set the mic input level to 0%, where the OS can trivially set i

On my T480s the mic mute button is handled in hardware/low-level firmware however all it does is set the mic input level to 0%, where the OS can trivially set it back to 100% if it wants. At least the LED on the button is driven by firmware based on that level, so it lights up only when the mic level is actually at 0%. While it won't prevent the OS from raising the volume, at least you'll know about it as the mute light will go off.