LrC: "Back Up Catalog": Ambiguous red warning after moving Lightroom folder to external disk

Environment: LrC 14.3.1 on macOS Sonoma 14.7.6.

I moved my LrC catalog (actually, ~/Pictures/Lightroom/) to an external disk on which I store my pictures, so I could attach the disk to another computer when needed.

Steps:

1. Ensure LrC is not running
2. In Finder, create the target folder on the external disk (/Volumes/ExternalDiskName/Lightroom)
3. Open Terminal.app
4. Type: cd ~/Pictures/Library/
5. Type: cp -pr * /Volumes/ExternalDiskName/Lightroom/
6. Type: cd ..
7. Type: mv Lightroom __old__Lightroom
8. Open LrC (note: in the previous step we renamed the local copy of the Lightroom folder so LrC would not find it)
9. Verify that you can access the images
10. Optional: move locally store files to external disk
11. Close LrC or open back up dialog (in my case, the last time I backed up the catalog was >1 week, so the backup dialog appeared when closing LrC)

When closing LrC the "Back Up Catalog" dialog appeared, with an ambiguous red warning. The weird thing is that the dialog correctly states "Backup folder: `/Volumes/mountedExternalDisk/Lightroom/Backups`" but I get a red message below this stating "The previously selected backup folder is not available. Catalog folder will be used for backup. Location: /Users/username/Pictures/Lightroom/backups".

Even when explicitly choosing `/Volumes/mountedExternalDisk/Lightroom/Backups` from within the dialog the red warning stays.

However, if I proceed backing up, the backup is correctly stored on the new location on the external disk.

To me it appears that LrC is confused after moving the folder containing the LrC catalog and backup folder. I would expect the red warning to disappear after explicitly setting (confirming) the updated backup folder location.