odd name of LUKS partition

[Piscium <groknok@gmail.com>]

Hi,

Recently I installed bullseye on a PC using netinst. During
installation I used the automatic installer and chose encrypted mode
with some space left empty. This is what I got:

root@backup-server:~# lsblk
NAME                            MAJ:MIN RM   SIZE RO TYPE  MOUNTPOINT
sda                               8:0    0 232.9G  0 disk
├─sda1                            8:1    0   512M  0 part  /boot/efi
├─sda2                            8:2    0   488M  0 part  /boot
└─sda3                            8:3    0 231.9G  0 part
  └─sdb3_crypt                  254:0    0 231.9G  0 crypt
    ├─backup--server--vg-root   254:1    0  45.6G  0 lvm   /
    └─backup--server--vg-swap_1 254:2    0   976M  0 lvm   [SWAP]
sdb                               8:16   0   3.7T  0 disk
└─sdb1                            8:17   0   3.7T  0 part

What I find odd is that the name of the LUKS partition is sdb3_crypt
and not sda3_crypt, which I would expect as it is in sda, not sdb. Any
ideas why this is so?