V12R1M504:

With APPLCOMPAT V12R1M504 on e.g. SPUFI or DSNTEP2, one can no longer create segmented or classic partitioned table spaces. See knowledge center for this restriction.
A small marginalia is behind this restriction, if this is combined with another fact.
In special cases DROP TABLE removes also dependent tables, e.g. DROP of an archive-enabled table (AET) drops the dependent archive table.

Scenario:

Assume an AET is in database 1 (DB_1), the table space type in this case is irrelevant.
The dependent archive table is in database 2 (DB_2), the table space type is an old-fashioned segmented table space.
Now DROP DB_1 is issued and this runs successful.
If the dependent archive table is in a universal table space (UTS), then DROP DB_1 results in:

SQLCODE = -669, ERROR: THE OBJECT CANNOT BE EXPLICITLY DROPPED. REASON 0001

Explanation:

The DROP DB_1 wants to drop also the AET table: this implicitly triggers the DROP of the dependent archive table, which could not run, because the dependent archive table is in a UTS. And UTS does not allow DROP TABLE. Refer again to SQLCODE-669.

With introduction of V12R1M504 this scenario could happen, because DDL CREATE syntax of an old-fashioned segmented table space creates a UTS Partition-By-Growth (PBG) table space.

If you ask yourself, why the author knows this and thinks this is remarkable: By running into the problem.