RAID 10 not showing full capacity

I am currently in the process of trying to setup a software raid using mdadm on my linux machine.

My system has 4x 8TB (all are exact same model) which I would like to put into a RAID 10.

However, after running

❯ sudo mdadm --create --verbose /dev/md/mdData --level=10 --layout=o3 --raid-devices=4 /dev/sda1 /dev/sdb1 /dev/sdc1 /dev/sdd1
mdadm: chunk size defaults to 512K
mdadm: size set to 7813893120K
mdadm: automatically enabling write-intent bitmap on large array
mdadm: Defaulting to version 1.2 metadata
mdadm: array /dev/md/mdData started.

lbslk only shows 9.7T and not the expected ~16TB of capacity on the Raid array:

❯ lsblk
NAME        MAJ:MIN RM   SIZE RO TYPE   MOUNTPOINTS
sda           8:0    0   7.3T  0 disk   
└─sda1        8:1    0   7.3T  0 part   
  └─md126     9:126  0   9.7T  0 raid10 
sdb           8:16   0   7.3T  0 disk   
└─sdb1        8:17   0   7.3T  0 part   
  └─md126     9:126  0   9.7T  0 raid10 
sdc           8:32   0   7.3T  0 disk   
└─sdc1        8:33   0   7.3T  0 part   
  └─md126     9:126  0   9.7T  0 raid10 
sdd           8:48   0   7.3T  0 disk   
└─sdd1        8:49   0   7.3T  0 part   
  └─md126     9:126  0   9.7T  0 raid10 
sde           8:64   0   7.3T  0 disk   
└─sde1        8:65   0   7.3T  0 part   
  └─backup  254:1    0   7.3T  0 crypt  /backup
nvme0n1     259:0    0 232.9G  0 disk   
├─nvme0n1p1 259:1    0     2G  0 part   /boot/efi
├─nvme0n1p2 259:2    0    32G  0 part   [SWAP]
└─nvme0n1p3 259:3    0 198.9G  0 part   /

I already tried doing it directly with the devices (as using /dev/sd{a,b,c,d} and also tried it with partitions that span the whole hard driveces /dev/sd{a,b,c,d}1

Can anybody tell me what I am doing wrong?

I found out that the parameter --layout=o3 causes this to happen. Without it the full hdd capacity gets used as expected.

Not sure what causes this behavior though.