The 2 disks in question were never formatted NTFS, so I don't know why they are being reported as fuseblk.
What I did:
I changed computers. I setup my new PC with Ubuntu MATE 22.04.1 and disconnected the old PC. I reconnected all USB drives and since I had access (same user - 1000), I thought nothing of it. Then I discovered this:
since I don't want to lose data, I do not want to format the disks. Will there be any issues leaving them as is?
no, you're fine 
cool. But they are formatted ext4 and not NTFS
The formatting doesn't matter.
The disk is mounted automatically when connected,
Therefore, mount is done by 'udev' -> 'udisks' -> 'fusermount'
When using 'Sytem Monitor' (which I actually never use, normally)
I see that my external drives, whether NTFS or Ext4, are also fuseblk mounted.
When using 'Disks' , it properly reports respectively NTFS and Ext4.
One thing though that puzzles me is that your 'sdc2' and 'sdf1' are not mounted through fuse. Are they by any chance mounted classically through '/etc/fstab' or any other way different from "plug in and go" ?
They were all mounted ext4 on old PC. When I plugged them all into the new PC this is what they identified as. I have never ever formatted any disks with NTFS.
Most portable disks are sold pre-formatted in NTFS.
They'll stay that way unless you explicitly format to something else
Did you explicitly format them as Ext4 when you started to use them ?
yuppers, formatted ext4
It can't change formatting without the data getting deleted.
Based on the premise that you didn't mix up disks, i give up.
This situation is, theoretically, impossible to exist.
I am surely baffled 
me too. I am almost 100% positive I formatted ext4, now you have me doubting that, LOL
Hello mickee
An old trick I use when formatting disks, usb-sticks etc.; I set the device name while formatting to the format-type e.g. ext4, exfat, NTFS, etc.. 
