mm2: size of target vs source topic

Hi all,
I'm setting up two new clusters today and using mm2 to replicate data from
clusterA --> clusterB. I noticed that the topic has the same amount of
record but the size is small by 5x.

source topic is 6.975 MB
target topic is: 1.136 MB

It has the same number of record. both cluster is using gzip. any idea why
this is?

thanks,