Xiaomi
Set a Daily Mobile Data Usage Limit auf Xiaomi
MIUI tracks data use per calendar month by default, so a single heavy day can slip past unnoticed until the monthly limit warns you far too late. A daily limit closes that gap by checking usage against a smaller threshold every 24 hours and resetting at midnight.
You set this up under Security ➔ Settings ➔ Data usage ➔ Data usage warning. From there, enable Daily data usage limit and configure both the Size and the action for When exceeded.
Two behaviors are available once the limit is reached. MIUI can send a notification only, leaving mobile data active, or it can disable mobile data automatically until you turn it back on. Pick the automatic shutoff if you are trying to avoid overage charges, and pick notification-only if you just want visibility.
A daily limit works alongside any monthly data limit you already have set, they do not replace each other. If your carrier resets your billing cycle mid-month or you use dual SIM, check that the daily limit applies to the SIM you actually use for mobile data, since MIUI tracks usage separately per SIM.