The iCloud app for Windows corrupts videos in some cases. Users will also see images that most likely belong to other iCloud users.
MacRumors is getting several user reports about the problem on its forum. For example, people with an iPhone 13 Pro and iPhone 14 Pro who synchronize a video with iCloud for Windows, among others, notice afterwards that the video is black with lines and, therefore, cannot be viewed. The users say that HDR and HEVC are enabled in their camera settings if they want to reproduce the error.
The situation becomes even more disturbing because the black images of the videos also contain images of strangers. For example, images of families, football matches or children pop up spontaneously. It is not clear where those images come from, but it does not seem impossible that these images from other iCloud users end up elsewhere at Apple due to an error.
It doesn’t seem to be a common problem. Some users report that they do not have the bug or cannot reproduce it. There are currently no similar problems reported on the Apple forum itself either.