When Fate/Grand Order first launched in Japan in August 2015 it debuted at #47 in AppAnnie’s App Store sales ranking. For the first time, it momentarily dropped outside of the top-50 at rank #59. [Thanks, Gamebiz.]
As shown in the above tracker, Fate/Grand Order dropped down rank #59 on June 1, 2019 at around 8:00pm JST.
However, keep in mind that it was a bit of an anomaly, as the game jumped back up to #37 moments after.
Fate/Grand Order is available on iOS and Android.