On Ubuntu 20.04, how to mount a LUKS2 partition?

After formatting an empty ext4 partition with

cryptsetup --type luks2 luksFormat /dev/sda1

I can open it with

cryptsetup open --type luks /dev/sda1 MyLabel

It is visible as /dev/mapper/MyLabel.

However, when I then try to mount it with

mount -t ext4 /dev/mapper/MyLabel /mnt/MyLabel

I get this error message:

mount: /mnt/MyLabel: wrong fs type, bad option, bad superblock on /dev/mapper/MyLabel, missing codepage or helper program, or other error.

What's wrong?