So, you did the same query for a user, and the bandwidth went up? This doesn't make sense for me. Are you sure you didn't push the Bandwidth while creating the 100k users?
Just questioning here, because we are currently building an app on top of firebase and this makes me suspicious...
When i request a user by id, it shouldn't make any difference if there are 100k or 1Mio Users, the result should be the same...