Before revision:   With vertical scaling, due to serial execution of validation commit phases of transactions, the allocated vCPUs are underutilized. With horizontal scaling,  due to redundant work between nodes , allocated resources are wasted though it is utilized.
After revision:  With vertical scaling, due to serial execution of validation commit phases of transactions, the allocated vCPUs go under-utilized. In contrast, with horizontal scaling, due to redundant work between nodes , allocated resources are wasted though it is utilized.