Well, hot dog!
I don’t even have xdg-desktop-portal nor xdg-desktop-portal-gnome nor xdg-desktop-portal-gtk installed. (None of them.)
Try uninstalling them and see if it resolves the issue?
Not sure of their purpose, but I’ve been using my Xfce system for a while now with no issues, without these packages.
To be clear, I do not have (nor ever have installed) any xdg-desktop-portal-*
packages.
EDIT: And here’s the bug report: FileChooser portal adds directories read-only (#41) · Issues · GNOME / xdg-desktop-portal-gnome · GitLab
Real bug report posted in below posts.
Which, once again, I don’t understand the need for these packages? Chromium behaves find without them, under Xfce and KDE, in which it uses the native KDialog or GTK file picker, depending on the environment, without any issues, and with full theme consistency and shortcut integrations.