Dear Great Man,
Welcome back to the Wefugees Community and thank you for reaching out to us again.
Unfortunately, I have no explanation for the changings on your "Duldung". Maybe in your municipality it is a mark for a certain type of Duldung!? Please see this thread for detailed information on the different types (Beschäftigungsduldung, Ausbildungsduldung etc.). I remember that we discussed the so-called "Duldung light" already, right? Here you may find the respective link again.
I hope another community member made similar experiences and can share it with you.
In any case, please don't hesitate to get back to us with any further questions and to update us if you were able to find out more.
All the best,