It takes bad luck for sure, but I once ruined a bunch (a big bunch) of my photos by syncing them to a NAS with a faulty RAM. It was a Synology Ds212 I think, back in 2012. Mind you, the device didn’t produce symptoms other than messing up regularly spaced bytes in the transferred files.
I am super paranoid about this kind of stuff and don’t consider a copy finished until it is first done copying then also passes an independent rsync -c.
