This stuff is literally everywhere, not just Google Photos. These people are hidden in plain sight, they hide in easy accessible sites that are large enough they can't be moderated fully, eg reddit, imgur, telegram, etc.. or private enough but still allow public sharing (literally any file storage platform). This won't stop until the internet as a whole is monitored, corporations forced to scan every file your put into the cloud. These disgusting people are eventually going to cost us our privacy (or at least what's left of it).  They always find other ways and other platforms, these people are a disease, it's a battle without ending.