2 new user accounts created when upgrading to 13.0.0

When upgrading to 13.0.0, I see that two new users were created:
“Ghost User”
“Gitlab Migration Bot”

I found documentation that the Ghost user is a container for relics of deleted users, however I cannot find any documentation explaining what the “Gitlab Migration Bot” user is for. Can anyone point me in the right direction?

Thank you,