Nearly every app that accepts user-generated content includes an agreement that you give them a license to use that content.

It's basically required for those apps to function. No platform would exist very long if users could upload content and then sue the platform for hosting it.

The agreements usually include a clause about allowing them to sub-license it.

So you still retain the copyright to the photos, but you can't sue them for using it.

> I'm wondering if this means 3 million copyright violations that could be litigated in civil court.

Outstanding observation! Class action suit in the making. Only lawyers get rich, but still could hurt the offenders financially.