Monthly Active Users(MAU) is wrong in the dashboard. Per the description on the graph:
Monthly active users (MAU) is the number of players active in a calendar month. A calendar month is the first day of the month to the last. Use this chart to see how your player activity changes month-to-month and trends over a large period of time. For example, an MAU of 35,000 for the month of July would mean 35,000 players had been active between July 1st and July 31st.
Yet the graph is not calculating that. It actually makes no sense since within the same month, the MAU value should never have drops in count as MAU is the cumulative amount of players within the month. At worst, the line should stay straight. Drops should only be expected whenever a new month rolls in, as this resets the player count.