I'm guessing Backblaze will come back with a more detailed report on this, but I wonder if the data already given to Facebook can be deleted properly (so that Facebook doesn't have it to use for other purposes elsewhere). Is that even possible to get done for a relatively large company like Backblaze?

Also, isn't this a violation of GDPR in EU, or is there a "you opted in by default when you logged in and so it's not our fault" argument in play here?