I've just realized (after being woken up by a notification in the middle of the night) that the Do Not Disturb mode is not present for the Mi Band 4, for both Mi Band 2 and 3 you could activate it by time or when the band realizes you are sleeping.
Why was a so useful function removed? I hope it will be coming back soon....
Why was a so useful function removed? I hope it will be coming back soon....