need help understanding Time Machine error

After dealing with this issue for several days, and running Disk Utility/First Aid on all the drives, and reformatting drives, with no change, I bought a new Samsung T7 2TB SSD for Time Machine backup storage. There have been no issues since installing the new drive 24 hours ago. I suspect macOS Monterey had issues with the G-Technology 1TB G-Drive I was using for Time Machine backup storage. I consider this issue resolved.

Backups are happening just not consistently. About 2 or 3 a day fail. I can click the Time Machine icon in the menu bar and see the status and I can open Time Machine from that icon's menu. I can read write to all drives and my external disks are connected directly to the USB-C ports.

Here is another error I just got: Time Machine could not back up the disk “T7” because a snapshot of the disk could not be created.

"T7" is a new Samsung T7 1gb SSD which can read/write fine and has 884.63gb available with 116.11gb used on disk. It's formatted APFS if that matters (my Time Machine backup disk is a G-Technology G-Drive 1gb HDD formatted Mac OS Extended (Journaled) and has 116.53gb available)

Any suggestions?.

Another backup just failed with the error: One of the disks being backed up may have been ejected or disconnected from the computer.

All disks are still showing on the desktop and are accessible in finder. What is going on?

And now, I just clicked Backup now from the Time Machine icon on the Menu bar and it completed successfully. It seems to be hit or miss if the backup will complete successfully. I don't understand what's going on with Time Machine.

I guess I spoke too soon. No disks were ejected or disconnected and the computer was plugged into power. I don't know how to mark this question as unanswered.

I just received an error:

Time Machine couldn’t complete the backup to “Samsung2tbPSSDT7Media”

One of the disks being backed up may have been ejected or disconnected from the computer.

2021-11-04 07:21:38 Checking destination IO performance at "/Volumes/Samsung2tbPSSDT7Media"

2021-11-04 07:21:39 Failed destination write test with error Error Domain=NSPOSIXErrorDomain Code=60 "Operation timed out". Wrote 17.7 MB in 1 file.

I was using a HDD when all these issues started and switched to an SSD and it didn't seem to fix it. I thought the problem was only on my MacBook Pro 2018 but I've seen it on my Mac Mini M1 also.

2021-11-04 13:44:07  Failed to find a disk matching UUID 260A1CEE-71C0-3A52-B538-6DAC0E9DDE83

2021-11-04 13:44:59  Mountpoint '/Volumes/G-DRIVE mobile USB-C' is still valid

2021-11-04 13:45:01  Failed to create session for '/System/Volumes/Data/Volumes/G-DRIVE mobile USB-C/Backups.backupdb' with options: 4, error: Error Domain=TMStructureErrorDomain Code=4 "SnapshotStorage - Structure missing" UserInfo={NSUnderlyingError=0x146f18fd0 {Error Domain=NSPOSIXErrorDomain Code=2 "No such file or directory"}, TMStructureStructureName=SnapshotStorage, NSLocalizedDescription=SnapshotStorage - Structure missing}

That explains it...my old Time Machine disk was Mac OS Extended (Journaled) format. When upgrading to Monterey it's too bad there's no alert to this fact.

I formatted the new disk with this machine in APFS format. I'm beginning to think it's just normal for Time Machine to ocassionally throw errors but I would hope not.