QR code login seems to be more reliable than normal OTP SMS request, which at times can't come. It's a feature present on desktop Mi Unlock. The prerequisite to do that is having the original Scanner app on a phone logged into the account (so not uninstalled, as it's present by default). If you don't have it, click the scanner button in quick settings panel and proceed to install (or get from apkmirror perhaps). Afterwards, you need to click the scanner icon in account settings, this icon won't get shown without the app.
QR code login seems to be more reliable than normal OTP SMS request, which at times can't come. It's a feature present on desktop Mi Unlock. The prerequisite to do that is having the original Scanner app on a phone logged into the account (so not uninstalled, as it's present by default). If you don't have it, click the scanner button in quick settings panel and proceed to install (or get from apkmirror perhaps). Afterwards, you need to click the scanner icon in account settings, this icon won't get shown without the app.