Xiaomi
Turn Auto-sync for Photos and Videos On or Off auf Xiaomi
Auto-sync for photos and videos runs through the Gallery app, not through general system settings. As soon as a Mi account is signed in on the phone, Gallery can mirror every new photo and video to Xiaomi Cloud in the background, which explains sudden storage warnings or unexpected mobile data usage.
To change this, tap on Gallery ➔ open the Menu ➔ tap on Settings. From there you can enable or disable Sync automatically directly. This toggle decides whether new media gets uploaded at all.
A second option, Only use Wi-Fi to sync photos and videos, lets you keep syncing active while blocking uploads over mobile data. This is the better fix if the goal is only to protect your data plan, not to stop cloud backups entirely.
Turning off Sync automatically completely does not delete anything already stored in Xiaomi Cloud. Existing backups remain accessible from other devices signed in with the same Mi account until they are manually removed from the cloud storage.
If cloud storage is full, new files will not sync even with the toggle enabled, since a full Mi account quota silently blocks further uploads rather than showing a permanent error.