The lead dev of Threads did an interview on the Hard Fork podcast on July 6, which is the day when Threads launched.

And he predicted the fast initial pick-up, the slow-down and then the drop-off of activity we see now, and covered how they'll grow it from there.

So none of this is truly news, it's expected. And normal. But of course Elon Musk's entourage on Twitter is having a laugh right now.