WTF?! Setting up your iPhone to back itself up to iCloud makes for the best syncing experience since it happens in the background in real-time. However, some folks like to have more control over their backups and opt to use the iCloud app. Unfortunately, a new bug appears to be fouling up the process for Windows users and putting every other iCloud user's privacy at risk.

Apple recently updated its iCloud website, giving it a more modern look and more functionality. However, Cupertino also seems to have borked the operation of the iCloud for Windows app. It's unclear if the two changes are related, but the Windows app is experiencing troubling issues.

Some users have reported to MacRumors that their videos are becoming corrupted and unwatchable when syncing with iCloud through the Windows app. Customers with iPhone 13 Pro and iPhone 14 Pros say that when they try to sync videos taken with their phone, the recording comes out black with scan lines.

Other users are conveying even more troublesome problems. Some say that when they attempt to watch the corrupted videos, additional pictures and videos from strangers appear in their iCloud library or in the corrupted video itself.

"iCloud for Windows is corrupting videos recorded from an iPhone 14 pro max resulting in black videos with scan lines," said one MacRumors forum poster. "On rare occasions, it is inserting stills into videos from unknown sources, possibly other's iCloud accounts. I've been shown photos of other people's families I've never seen in my life, soccer games, and other random photos. Obviously, this is extremely concerning and does not exactly make me feel safe using iCloud."

Indeed, if photos and videos from other iCloud users get shuffled randomly into other people's accounts, Apple has a serious privacy issue. Even if it is isolated to the Windows iCloud app, the ramifications for users, in general, are concerning. If random images appear in Windows users' accounts, how can Mac users be sure it's not their pictures being shared?

We have reached out to Apple for comment but have not heard back. We'll update this story if it provides further details.

On the bright side, a search of Apple's dedicated iCloud support community has no recent posts regarding this issue, despite MacRumors forum users saying they have reported it. Likewise, other than tweeted coverage of the problem, users are silent on Twitter. So far, the only reports seem to be coming from MacRumors forums. The whole thing might be someone's bad joke that snowballed and got out of hand, but until Apple responds, be cautious when backing up your phone.