Important naming clarification up front (this causes a lot of confusion):
The legacy Xiaomi Miio integration in Home Assistant core is now shown in the UI as “Xiaomi Home” (green icon). This is not the same thing as the new official Xiaomi OAuth-based Xiaomi Home integration. In this post, when I say “Miio (now known as Xiaomi Home)”, I mean the legacy token-based integration, not the new OAuth one. This naming overlap is a big part of why this topic is so confusing.
TL;DR