GBB/AUI DEBIT/CREDIT INDICATOR

[babyco]

Hello.

I upgraded the version from S/4HANA 1709 to S/4HANA 2023.
Activity settlement is done through GBB/AUI - PRL setting in CKMLCP. (Actual cost calculation indicator = 2)

[Before upgrading the version]
GBB/AUI FI DOCUMENT - DEBIT/CREDIT INDICATOR(BEKNZ)= ‘S’ OR ‘H’

[After upgrading the version]
GBB/AUI FI DOCUMENT - DEBIT/CREDIT INDICATOR(BEKNZ)= 'A'

I found SAP documents related to this, but I couldn't find them.
May I know the cause and document for these changes?

Thank you.