Thank you for your support of Xiaomi products, and we apologize for the trouble you're experiencing. In some cases, noise at maximum volume during hands-free calls can occur, especially in certain situations when the signal is weak or certain APPs are being used. We have addressed this issue in the latest system update, and you can resolve the problem by upgrading to the newest version.
Additionally, you can try restarting your device after the update to ensure all optimizations take effect. After updating, it is recommended to avoid prolonged use at maximum volume to maintain optimal audio clarity and protect the speaker hardware.