No, I think it's just me on my instance (that probably has the capacity for 1000+ active users) and the steady influx of suspicious accounts that pass the email verification and captcha and then either post nothing, or post adverts get banned/deleted and it goes on.
Mind you I don't really advertise the instance either. So that's likely why.
I suspect people coming from reddit don't understand the fediverse (I know I didn't when I first got here). So they go to the hosting instance and join there, not really understanding they can join any instance and then join the community (if not already on the instance).