On rare occasions, it is inserting stills into videos from unknown sources, possibly others iCloud accounts.
Obviously, this is extremely concerning and does not exactly make me feel safe using iCloud, explainedMacRumorsreadersleeping_ghost.
I made a new account just to post about this.
I am facing the exact same problem.
I recently re-installed iCloud for Windows from the Store and started syncing again and got the problem.
I am running Windows 11 Home on my PC and my phone is iPhone 13 Pro.
Also for me all my videos seems to have this issue, wrote anotherMacRumorsuser Sribeno.
source: www.techworm.net