Update v1.3.0.rst

whatsnew entry

Author: jackzyliu

doc/source/whatsnew/v1.3.0.rst

@@ -974,6 +974,7 @@ Other
 - Bug in :meth:`DataFrame.convert_dtypes` incorrectly raised ValueError when called on an empty DataFrame (:issue:`40393`)
 - Bug in :meth:`DataFrame.clip` not interpreting missing values as no threshold (:issue:`40420`)
 - Bug in :class:`Series` backed by :class:`DatetimeArray` or :class:`TimedeltaArray` sometimes failing to set the array's ``freq`` to ``None`` (:issue:`41425`)
+- Bug in :meth:`_CustomBusinessMonth.apply` not applying extra offset when initially rolled date `new` is already a business day (:issue:`41356`)
 
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