When creating a pool, use disks with the same blocksize. A correlation between zfs "blocksize" and the disk blocksize is the ashift parameter (which cannot be modified after the pool creation). Either the value is set to "0" for auto blocksize recognition, or manually set to either ashift=12 for 4k blocksize disks or ashift=9 for 512b blocksize disks. Mixing disks with different blocksizes in the same pool can lead to caveats like performance leaks or inefficient space utilization.

You can interact more effectively with ZFS using the zdb tool. To check the vdev ashift used for the zpool, check the ZFS MOS configuration:

zdb -C <pool_name>

or

zdb -e <pool_name>