MongoDB has enhanced its time synchronization by introducing a global logical clock, which enables multi-document ACID transactions and provides a consistent view of time across the entire sharded cluster. This hybrid logical clock combines system time with operation counters to create a timestamp that is gossiped throughout the cluster, allowing for synchronized clocks across nodes and shards. The introduction of this clock mitigates issues such as tampering with timestamps, which could compromise the system's ability to accept new modifications. With the global logical clock, transactions can be coordinated and synchronized more easily, making it an essential foundation stone for the scope of transactions in MongoDB 4.2.