This is an expected statistical artifact given the "last month" aggregation and a huge influx of new users of which many don't stick around. I am saying they don't stick around, because that's generally just what happens with a lot of new users (e.g. they checked it out, decided it's not for them) and also due to the federated nature they might have switched accounts and similar things. Then the bit about "last month" aggregation: Have a look at the "Active 6 months" graph - it's still trending upwards. Those are likely a trailing average aggregations, so a maximum is reached when that 1-month-window starts (roughly) at the beginning of the huge user influx. For the 6-month window that hasn't happened yet, so still going upwards. Assuming nothing changes (similar amount of new/leaving active users) the graphs gonna be interesting in the next few weeks: After the initial wave of influx the balance was most likely negative (more users from "the wave" dropping out again than added users afterwards), however I'd hope it's gotten positive since then. If that's the case the graph should start trending upwards 1 month after the balance became positive. It's unclear when that was the case, but some towards end of July might be a reasonable guess? The same graph with a smaller window could shed some light on that (or just expose useless noise ¯_(ツ)_/¯ ).

Another sign I'd consider good: The active user ratio is trending upwards.

Disclaimer: I don't know how the data is aggregated, nor how exactly "active" is defined - the gist of the above very likely applies though. I was too lazy to look it up in the code - if someone knew how these graphs are aggregated and were so kind to let me know, that'd be appreciated :)