There are lots of reasons that affect testing results to be inaccurate, like before/after eating or exercising, morning/night differences, standing posture, or floor material.
Additionally, the Xiaomi Body Composition Scale has an extremely sensitive sensor that requires measuring on a hard, flat floor for accurate results. The Xiaomi Body Composition Scale may also calculate its weight. If not used for a long time, you can ignore it and redo the measurement after the auto-off timer.