My instance had 5 users after a few days, two of which were my own.

Then one day later there were over 600 users registered on my instance.

All of those 600+ new users were spam bot accounts.

Lemmy is sorely lacking the tools for dealing with that kind of thing.

So in order to avoid that the spam accounts that were created could cause problems for other instances, I temporarily shut down my instance until there are tools that I can use to deal with the spam accounts.

https://zapad.nstr.no/

I wonder how many of the 2M users mentioned in the OP story are real persons, and how many are spam accounts.