Weird users trying to create logins

I have noticed for the last couple of weeks I have had 20/30 new users every day who do not verify their email address. I’ve checked multiple times that the verification works and it does.

I don’t think that these users are real and one new user is DEFINITELY not real. For example, here are some new users in the last day
ffdfgsjgieyriwffdf78987
ffdfgsjgieyriwffdf89185
ffdfgsjgieyriwffdf55285
ffdfgsjgieyriwffdf37156

I don’t understand why these users keep attempting to join using the same username?
There are also a wholleee bunch of random ones who appear to have absolutely no activity on the site, or who even don’t activate their email.
I’ve got an email address blocker, but these new users are joining with @gmail.com @yahoo.com, so the email blocker doesn’t stop those.

What can I do about this? It seems quite malicious in some way but I don’t fully understand their intentions…