Problem with Read-Only Access

[Mikenux]

When I grant read-only access to a file in the file chooser, it seems to be not.

Steps to reproduce:

1. Install Metadata Cleaner (from Flathub).
2. Launch Metadata Cleaner and add a file with the Add Files button (top left in the headerbar).
3. Select a file with metadata (e.g. an image), and check "Open Files Read-Only" in the file chooser. (Don't forget to backup your file if needed)
4. Check if there is metadata (there is number next to the filename), then click on "Clean" button (bottom right) if there is.
5. A dialog to apply the operation appears.
6. Click on "Clean" and the file is cleaned (this can be verified by re-opening it or seeing its size).

If I gave read-only access, the file should not be writable. This may be the case since a dialog box appears and I validate with "Clean", but this dialog box seems custom when it should not be. Also, if I check the "Don't tell me again" box, it no longer prompts me for confirmation, but therefore overwrites (in my opinion) the read-only option if I check it the next time: I should be warned of the writing even if I checked "Don't tell me again".

OS: Fedora Workstation 38, GNOME. Posted here as the gtk file chooser is what is used in GNOME.