Can't open portal file chooser

Whenever LibreWolf prompts for the File Chooser (pick a file on the computer, or download with download.useDownloadDir set to false, mostly), it fails silently, while outputting a warning only on the terminal:

(librewolf:2): Gtk-WARNING **: 01:58:21.453: Can't open portal file chooser: GDBus.Error:org.freedesktop.DBus.Error.UnknownMethod: No such interface “org.freedesktop.portal.FileChooser” on object at path /org/freedesktop/portal/desktop

I have some weeks ago nuked the additional Flatpak packages that LibreWolf prompts to install from the .flatpakref and some additional Gnome packages on apt, but haven't really noticed if the error began right then. I have then installed again from the .flatpakref, reinstalling the missing packages, and the issue didn't go away.

Interestingly, File Choosers that support drag-and-dropping also doesn't work.

What I currently do as a workaround for download is to have download.useDownloadDir set to true, download in my download dir and then move to the desired place. Which is a major inconvenience.

I have migrated from POP!OS, and have kept my home folder, but it has worked as normal for quite some time before behaving like this.

I have already tried:

• Reinstalling the Flatpak packages I nuked earlier;
• Running with MOZ_DBUS_REMOTE=1 set at launch with flatpak run --env=MOZ_DBUS_REMOTE=1 io.gitlab.librewolf-community;
• Running flatpak repair io.gitlab.librewolf-community;
• Checked that xdg-desktop-portal is actually installed;
• Installed xdg-desktop-portal-kde;

Debian 11 Bullseye (LTS)
LibreWolf 92.0
Flatpak 1.10.2