User permissions for sharefolder - what are userID 1001,1002,1003 and 1004?

Hi guys,

with the screenshot you will see the users: 1001,1003 and 1004. In one other sharefolder there has also the user 1002 access. So can someone tell me, who are these users?

No one, who can explain the users? Is that a security issue, which should be solved?

Merci, so hopefully they will deleted with one of the next updates, or?