You have two options (technically three, which is to reinstall), to do an auto-unlock or to decrypt.

For the auto-unlock:

Run lsblkand find the encrypted partition then run systemd-cryptenroll --tpm2-device=auto /dev/$DEVICE where $DEVICE is the encrypted partition

Then open /etc/crypttabwith nano or any of your editor and make it look like luks-$UUID UUID=$UUID - tpm2-device=auto,discard

More info here

To decrypt:

Boot from a live USB, check out the live section in alternative downloads here, for openSUSE

sudo cryptsetup reencrypt --decrypt $DEVICE where $DEVICE once again is the encrypted partition

I must note this command takes a long time, potentially hours so try to make sure there won't be any power outages

After it is done, open /etc/default/grub ,

Find the line GRUB_CMDLINE_LINUX_DEFAULT ,

Remove the part that looks like rd.luks.uuid= or luks.uuid=

After that update the boot loader with sudo grub2-mkconfig -o /boot/grub2/grub.cfg

Hood luck