Why are third-party users logged in?

Question

System administration

Please tell me why I see third-party users in the Security Log: its name matches the name of our PC, with the exception of one character that has some kind of left, previously unknown domain? What is it? For some reason, I also cannot disable the Group Policy Client service. How in general does the system allow the entrance of anyone incomprehensible ???

Answer 1

With a $ sign at the end, these are not users, but computers.
Yes, they can get in too.