What triggers the delivery status VBUK-GBSTK to 'B'?

Hi.

I encounter an issue with regard to the delivery 'Overall status' (VBUK-GBSTK) upon delivery creation. In my understanding, upon delivery creation, GBSTK status should be initially at 'A' but when I create my deliveries, upon saving, my document GBSTK status becomes 'B'. Whereas for my other deliveries their statuses remains at 'A'.

Is there a control or configuration somewhere, that controls the status change upon delivery creation?

Appreciate the expertise and support for my issue from the community.

Thanks!