Your phone and computer likely back up your data (photos, messages, etc.) to the cloud automatically. If someone has access to your account (e.g., your Apple ID or Google account), they may be able to see all of your backed-up data.

Shared albums in iCloud or Google Photos can be a way for someone to see your new photos without you actively sending them. Review who has access to your shared albums and remove anyone you don't trust.

If you are signed into the same Apple ID or Google account on multiple devices (like an iPad and an iPhone), your messages, photos, and browser history may be syncing between them. An abuser could be using a secondary device to monitor your activity.

The best way to secure your backups is to secure the account itself. Use a strong, unique password and enable multi-factor authentication (MFA). You can also review which devices are signed into your account and sign out any you do not recognize.