If the registered number is no longer active, you can submit an unlock application to Xiaomi’s support team with proof of purchase to have the lock manually removed. Technical Bypass for MIUI V12.5.1.0

Visit the Xiaomi Account login and select "Forgot Password" to receive a reset link via your registered phone number or email.

This typically requires putting the device into Fastboot Mode (Power + Volume Down) or using a dedicated flashing method to overwrite the Mi Account data partitions. Factory Reset (Screen Lock Only) Phone Unlocking Q&As - Xiaomi

If you have access to the phone number or email associated with the account, use the official Xiaomi reset page to regain control.

Tools such as Hydra Tool , Chimera , or the Mi Flash Tool are frequently utilized to flash authorized ROMs or patch account data.

Specific .zip files for MIUI V12.5.1.0 (Android 11) allow for account bypass through flashing, often working on both locked and unlocked bootloaders. Platforms like Android File Host and HalabTech host these recovery images.