Disk Errors

Here are some steps that may help.

1. Back up your Mac.
2. Start up your Mac in macOS Recovery over the internet (Option-Command-R).
3. Erase your Mac.
4. Install a clean copy of macOS Big Sur.
5. Set up the Mac as new. Manually copy user data. Install third-party applications from the App Store or developer website.

Contact Apple Support for further assistance.

I know of no 3rd party disk utility that properly handles APFS. The Apple Disk Utility is running the command line "fsck_apfs -y -x [device]" command under the hood and displaying the output in the GUI interface. You will have much better luck repairing any soft errors on the internal disks by booting from an external drive and running the repairs on the internal drives while not in use.

Re-download the macOS Big Sur installer from the App Store so you have /Application/Install macOS Big Sur

[Optional] You can do this from the Terminal command line:

sudo softwareupdate --fetch-full-installer --full-installer-version 11.4

Burn a Big Sur installer USB flash drive

[https://support.apple.com/en-us/HT201372]

Format as HFS+ and name the flash drive MyVolume.

sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume

Ensures the internal drives are NOT in use. Boot from the USB Big Sur Installer flash drive and run Disk Utility. Select View All Devices.

First Aid depends on the item which is selected. If that’s a disk, then First Aid checks and repairs at that level, including the disk’s partition map and EFI partition, not its volumes. To perform full checks on an APFS volume, you should select that volume (not its disk or container) before clicking on the First Aid tool. To check and repair all volumes in a container, you must first eject each of its volumes, then select the container and click on the First Aid tool. Or run First Aid on them individually.

To summarize, run Disk Utility at the top level and work your way down to each individual volume.

If the disks cannot be repaired, you will need to completely erase the internal drives and re-install macOS then restore your data from backup. Providing the disks do not have hardware faults this may be the only sure way to fix the file system. The Fusion drive was likely upgraded to APFS from HFS+ and perhaps a bug occurred. This would rebuild the Fusion pairing and format it cleanly with APFS.

After erasing the Fusion drive pairing it will likely be split showing two drives. Follow this KB to rebuild the Fusion drive pairing:

https://support.apple.com/en-us/HT207584

Then you can install macOS Big Sur back onto the Fusion drive and continue.

nordvpn.osx.helper- VPN are virtual private networks which can mess your internet connection.

Little Snitch is a packet sniffer and can get overzealous. Remove it.

AppCleaner is malware.

You have multiple backup solutions like Backblaze running concurrently as well as Amazon Cloud.

You should only one any backup solution one at a time. If you do multiple they can run into each other trying to figure out who has access to the data.

With multiple network access software, you also are at the whim of the asynchronous internet where uploads are slower than downloads.

Keep it simple. Isolate. Backup as a clone to an external hard drive using Carbon Copy Cloner. Make sure your hard drive is no more than 85% full.

Any application you aren't sure if you really need, you can drag and drop into AppDelete and it will remove all the components for you while in safe mode (shift key boot):

http://www.reggieashworth.com/appdelete.html