After zfs send lz4 is less efficient?

[kdragon75]

Im shuffling disks and as such im using zfs send | zfs recv and found a strange result. After sending 3.8TB, its 4.1TB. Looking at the datasets/zvols and their sizes/compression ratio, this accounts for the increase in space. but WHY?

Did lz4 compression change?

 

[Apollo]

possibly due to pool configuration, level of fragmentation...
Snapshot account for space too.