Pushdown optimization to the source stops at the partition point <transformation name> because the source has a partition with an end key- range different from the start key range of the next partition.
You configured the source for key range partitioning, but you did not ensure that the end key range for a partition matches the start range for the next partition. The end key range for each partition must equal the start range for the next partition, and it cannot overlap with the next partition.
Modify the start or end key-range to ensure that the end key range for the partition equals the start range for the next partition.