Redis the question about replication command

I encountered a problem when doing dual-active synchronization in remote data centers. In Redis version 4, the propagated commands will not be rewritten. The incoming command is 'Setex', and the master node synchronizes to the slave node with 'Setex'. Therefore, the circular replication problem in the two data centers can be filtered and distinguished by identifying the difference in commands in the middle layer. For example, the commands for redis bilateral replication are all through SETEX, and the commands written by the service are all 'setex'. The synchronization service filters 'SETEX' and does not perform circular replication. However, after upgrading to Redis version 6, 'SETEX', 'setex', etc. will be uniformly rewritten as SETEX and propagated to the slave node. May I ask why all commands need to be uniformly rewritten as 'SETEX'. In this way, if dual-center data synchronization is required, a new solution may be needed