Comment 4 for bug 1971168

Steps to reproduce:

1. Run Firefox (version 99.0 or 100.0b9) as a Snap package in Ubuntu 22.04 (upgraded from 21.10)
2. Have a SMB file server available where the network shares can be mounted just by clicking on the share in Nautilus file manager (smb:// protocol, usually mounted dynamically via `/var/run/user/.../gvfs/...`)
3. Have one such share mounted and writable
4. Open any website containing images in Firefox
5. Right-click on an image and select "Save Image As..."
6. In the file save dialog, navigate to the mounted share
7. Assert content of network share is visible and browsable from within the save dialog
8. Select "Save" at any folder in the network share

Actual results:

* File is not saved to selected network share location
* No file download entry is created in "Downloads"
* No error is shown

Expected results:

* File is saved to selected network share location
* No error is shown

Additional information:

* When saving to a folder on the local machine instead, saving works correctly as expected
* In contrast to files, new folders that are created from within the save dialog are saved correctly on the network share