The European Union's General Data Protection Regulation had a tangible impact on Facebook's user base -- if only just. While discussing its second quarter earnings, the social network revealed that it lost about 1 million monthly active users in Europe due to the implementation of GDPR. That's a drop in the bucket next to Facebook's 376 million European users and 2.2 billion total users, but such a decline is extremely rare for a company that has almost always seen growth, even if it has been slowing over time.