LVM merge destroyed hard drive

I tried to upgrade from Kubuntu 22.04 to 22.10, and borked it. Accidentally pressed Ctrl-C with the terminal window active. I think I was able to fix everything, but didn't want to chance it.

I had an LVM snapshot, so I tried to restore it from a live USB, and this seems to have destroyed the hard drive. I am completely mystified.

To create the snapshot, I did the following (this is from memory):

sudo lvcreate --snaphot --name Kubutu-snap --size 20G /dev/vg1/Kubuntu

To restore the snapshot:

sudo lvconvert --merge /dev/vg1/Kubuntu-snap

After I saw "Merge 100%" and the command terminated, I restarted the computer. Upon reboot, I got a message about my hard drive being missing.

Further info:

• I was a bit hasty pulling the flash drive from my computer after restarting. But I don't see how this could kill the internal drive.
• I don't know if the snapshot was overfull. I would have thought that there would be a warning if this were the case. I also can't see how this would hurt anything beside than the logical volume in question.
• The drive is a SATA SSD.
• I was connected to power the whole time.
• sda used to be my SSD. sdb is the live USB.

Debugging. Upon rebooting to my live USB, it is unclear what is up with the SSD. df gives nothing.

lsblk is unhelpful.

$ sudo lsblk
...
NAME   MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
(loop devices)
sda      8:0    1     0B  0 disk
sdb      8:16   0  29.2G  0 disk 
├─sdb1   8:17   0   3.4G  0 part /cdrom
├─sdb2   8:18   0   4.1M  0 part 
├─sdb3   8:19   0   300K  0 part 
└─sdb4   8:20   0  25.8G  0 part /var/crash
                                 /var/log
...
$ sudo lsblk -o UUID,NAME,FSTYPE,SIZE,MOUNTPOINT,LABEL,MODEL
...
UUID                                 NAME   FSTYPE     SIZE MOUNTPOINT               LABEL                   MODEL
(loop devices)
                                     sda                 0B                                                  SD/MMC
2022-04-19-10-22-47-00               sdb    iso9660   29.2G                          Kubuntu 22.04 LTS amd64 Extreme
2022-04-19-10-22-47-00               ├─sdb1 iso9660    3.4G /cdrom                   Kubuntu 22.04 LTS amd64 
8D6C-A9F8                            ├─sdb2 vfat       4.1M                          ESP                     
                                     ├─sdb3            300K                                                  
783b59ea-3cd8-4ef9-95e1-0d7cc906e5e6 └─sdb4 ext4      25.8G /var/crash               writable 
...

smartctl is unhelpful.

$ sudo smartctl -d scsi -a /dev/sda
...
=== START OF INFORMATION SECTION ===
Vendor:               Generic-
Product:              SD/MMC
Revision:             1.00
Compliance:           SPC-4
Logical Unit id:      0x00e04c2020202000error: designator length
Serial number:        2012090114345300
Device type:          disk
Local Time is:        Fri Dec 23 23:39:16 2022 UTC
NO MEDIUM present in device
A mandatory SMART command failed: exiting. To continue, add one or more '-T permissive' options.

Clearly, "SD/MMC" is not correct.

So, the questions:

1. What on earth happened?
2. Can I fix this?