Vendor reconciliation account &1 account was changed to &2 (see longtext)

What causes this issue?

During document processing the Vendor reconciliation G/L account &V1&
was overwritten with account &V2&. This is not allowed for down
payments.
The most likely cause for this problem is the account assignment
transfer customizing for earmarked funds. In this customizing the G/L
account should not be transfered in rules assigned to activity
"Reduction from down payment" (AZBU) and "Reduction from Down Payment
request" (AZAF).

System Response

The document is not posted

How to fix this error?

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Procedure for System Administrators

Change the customizing in IMG activities
<DS:SIMG._ISPSFM_OFMR3>Define Rules for Account Assignment Transfers</>
and <DS:SIMG._ISPSFM_OFMR5>Assign Rules</>

Error message extract from SAP system. Copyright SAP SE.