If you check the other comments you'll see that Spotify, Snapchat, Discord etc. were all affected. We're not talking about "sites" but any application or site built on Google's infrastructure, even partly.
Pokemon Go
Not "every application," just applications making use of the GLB or services built upon it.
I'm not sure if it is related but Google developer console (for Android apps) stopped displaying total number of installs today
Snapchat, Spotify, Discord,...
Thanks for the information. I see now why I hadn't noticed. I don't Snapchat anymore, I switched to Google Music, and I haven't adopted Discord. I guess I'm not in with the cool crowd anymore!