Pushdown optimization to the source stops at the transformation <transformation name> because it is a partition point and the partition type is not hash auto-keys or pass-through.
To push transformation logic for a partitioned transformation to the database, the partition type must be hash auto-keys or pass-through. If the partition type is hash auto-keys, the source must be key-range partitioned, and the key ranges cannot gap or overlap.
Change the partition type for the transformation to hash auto-keys or pass-through.