The Xiaomi Air Compressor 2 Pro is mainly designed to pump air into tyres or other inflatable objects. It has an automatic pressure detection function that stops it when the preset pressure is reached. There is no specific function that allows air to be released from a tyre by reducing the pressure. So if you have a tyre with 3 bar pressure and you have set 2.8 bar, the compressor will not automatically release the excess pressure. You would have to manually reduce the pressure by releasing air from the tyre before using the compressor.