According to the graph it accounts for active users within the last 30 days. 30Days ago the reddit strike started and an influx of people started posting. I wouldn't be surprised if a lot of people haven't been here since. There was a lot of performance and other issues with lemmy&kbin at that time.

I don't think lemmy is still growing. I might be wrong but this graph https://fedidb.org/current-events/threadiverse
is trending down and i've seen a lot of smaller magazines/communities that haven't had any posts for 1-2weeks by now.
I try to help that problem at little but i doubt lemmy&kbin has >100k active users right now.