It appears that Google Photos is having a bit of a moment. It seems that it’s corrupting some older images stored on the service dating from 2013 to 2015, according to reports from users. The phenomenon shows up as what looks like digital tears (as in rips through the image, not liquid that comes from your eyes) across the image, as you can see in examples posted to the Google support forums.
Quite a few people have reported the issue. As well as post on Google support, there are also a number of Reddit threads with more examples. There is some good news, though. It looks like Google is already on the case and some users have had their images fixed without them having to do anything. But, if you’re facing this issue and it doesn’t get automatically fixed, there is a way to do it yourself.