It looks like about 1000 new accounts were created/became active on that day.

I remember @antik@lemmy.world mentioning similar numbers, so that's probably this.

We should stabilize somewhere in 30,000 range for MAUs before the end of the year

That's what I foresee as well.

so we can have more sports fans and humanities types

Discoverability of those communities is probably the first issue to fix. I tried to address it a while back, maybe I should do another one of those posts: https://discuss.tchncs.de/post/2410183