Try to watch your video on PC. Or try to talk louder. The mic in Xiaomi is not very sensitive and it seems you to talk not loud. So maybe the sound in your video is too quiet. Usually I need to amplify sound in my video on PC before sharing it
I tried lower fps, 30 - 48 and still no voice.. i tried also to talk louder, and it didn't worked.. i just hear something like 'shhhhhh', but no voice...
I got on screen like 'You can't record in this resolution' or something like that when i choose 720p..
This should be mic issue (hardware or software?)