On mantic the situation is different because nautilus uses the email portal now which add attachments by crafting a mailto: url, which thunderbird doesn't handle, see https://github.com/flatpak/xdg-desktop-portal-gtk/pull/447
On mantic the situation is different because nautilus uses the email portal now which add attachments by crafting a mailto: url, which thunderbird doesn't handle, see https:/ /github. com/flatpak/ xdg-desktop- portal- gtk/pull/ 447