While the Mi A3 continues its wait for Android 10, its predecessor received its final OS upgrade last month. The upgrade path to Android 10 for the Mi A2 has not proven straightforward though, with it being possible that Xiaomi has pulled the OS upgrade for the second time because of bugs.
https://www.notebookcheck.net/Xiaomi-may-have-pulled-the-Android-10-update-for-the-Mi-A2-again.454361.0.html