https://www.gsmarena.com/xiaomi_will...news-44589.php
Xiaomi has officially confirmed that it will no longer release handsets running Android One, which in turn means that there won't be Mi A4. There's no specific reason for the discontinuation of the lineup but our educated guess would be the issues Xiaomi was facing with the software when providing updates to these phones. They were often late even though the Android One program is all about swift updates and longer support.