Repeatable blocks automatically add user in "user" field

Hello!

When we clone a group, it automatically adds the first user available in the user list. It should be empty as default but it's not.

See video for clarification:
https://imgur.com/a/RbrJWns

Our json code: https://pastebin.com/FDfTkjEW

Please let us know how we solve this.
Thanks