Xiaomi
Auto-Update Download Settings auf Xiaomi
MIUI checks for firmware updates in the background and, depending on one setting, downloads them automatically once they are found. This is separate from whether you get notified about an update — it only controls whether the download itself starts without you tapping anything.
If this toggle is on, a full update package can download over Wi-Fi or mobile data as soon as it becomes available, which sometimes surprises users with a sudden storage or data usage spike. If it is off, updates still appear as notifications, but you have to start the download yourself each time.
There is a second, related setting that only affects whether downloads are allowed over mobile data, so the phone does not silently burn through your data plan. Turning that one off does not stop automatic downloads over Wi-Fi, it only blocks them on cellular.
Where to find the setting
Open Settings ➔ About phone ➔ MIUI version ➔ Open the Menu ➔ Update settings, then enable or disable Download automatically.
If you mainly want to save mobile data rather than block downloads entirely, look for the separate mobile data option in the same screen instead of turning this toggle off completely.