Why is there a mark on the fingerprint position of the Xiaomi 15 Ultra screen?

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The Xiaomi 15 Ultra is equipped with advanced ultrasonic fingerprint technology, which provides a secure and fast fingerprint recognition experience. Unlike traditional optical fingerprint sensors, the ultrasonic sensor uses sound waves to map the fingerprint in great detail, allowing it to function effectively even when the screen is wet or dirty. This technology requires the fingerprint sensor to make direct contact with the screen surface for optimal performance.
It is important to note that under bright daylight or direct sunlight, you will notice a slight screen mark at the position of the fingerprint sensor. This is a normal phenomenon and is a result of the way ultrasonic sensors work.