The Mi Max 3 and Mi Mix 3 5G have received new MIUI 12 updates, bringing the two devices on Xiaomi's latest OS. The Mi Mix 3 5G still remains on Android 9.0 Pie in Europe on the Vodafone network, but the global and Russian versions of the Mi Max 3 have been upgraded to Android 10 builds of MIUI 12.
https://www.notebookcheck.net/The-Xiaomi-Mi-Max-3-and-Mi-Mix-3-5G-receive-new-MIUI-12-updates.498658.0.html
What is not mentioned is the absolutely horrible amount of advertising on xaiomi phones, Xaiomi did something to their MUI that allows add to load in background and if you want to open or close an app you can be met with raucous music for ads which can last for 5 to 10 secs, one can limit and restrict app permissions from WiFi and mobile data but it's already too late, I would NOT recommend buying a Xaiomi phone,
I've got a Mi Max 3 with eu.rom which updated to Android 10 MIUI 12 a good couple of months ago. This comes without any ads, plus I've rooted, so can take further measures to avoid unwanted ads. The phone has amazing battery life and is great for viewing media and reading.