Xiaomi has introduced the January 2022 security patch update to the Mi A3, the final Android One smartphone on its books. V12.0.18.0.RFQMIXM is rolling out now as an OTA and is available as fastboot or recovery ROMs.
https://www.notebookcheck.net/The-Xiaomi-Mi-A3-receives-another-update-with-the-January-2022-security-patch-upgrade.593402.0.html