Deferred_Segment_Creation and adding partitions to Reference type partitioned tables

When I add partitions to the referenced table in Oracle 19c (19.7), deferred_segment_creation seems to be ignored. When the tables were created, no segments were created. But when I alter the referenced table to add partitions (split into full years worth of partitions in one statement), every new partition for the partitioned tables (10000s of segments) was created (8M for tables, 64K for indexes). Does anyone know what is going on? Do I have any option to get rid of the segments without shrinking and fragging the tablespace? This is a vendor database where most