Flatpak app can’t open links

I don’t know much about flatpak, so not sure where to look for. I can’t open links from thunderbird flatpak to firefox flatpak. I’ve looked around it seems that it should be an problem with *portals*. Yet, when I try to debug with flatpak run --log-session-bus org.gnome.Maps, the logs don’t seem to show anything wrong with portals when clicking on a link in the app (at least I don’t see it):

C63: -> org.freedesktop.DBus call org.freedesktop.DBus.AddMatch at /org/freedesktop/DBus
C64: -> org.freedesktop.DBus call org.freedesktop.DBus.AddMatch at /org/freedesktop/DBus
C65: -> org.freedesktop.DBus call org.freedesktop.DBus.StartServiceByName at /org/freedesktop/DBus
B40:  org.freedesktop.DBus call org.freedesktop.DBus.GetNameOwner at /org/freedesktop/DBus
B43:  :1.80 call org.freedesktop.DBus.Properties.GetAll at /org/freedesktop/portal/desktop
B1171:  :1.80 call org.freedesktop.portal.OpenURI.OpenURI at /org/freedesktop/portal/desktop
B1172: <- :1.80 return from C68
B1175: <- :1.80 signal org.freedesktop.portal.Request.Response at /org/freedesktop/portal/desktop/request/1_715/gtk2129782386

I don’t get it. Thoughts? My OS:

6.2.0-36-generic #37~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Mon Oct  9 15:34:04 UTC 2 x86_64 x86_64 x86_64 GNU/Linux

flatpak version:

Flatpak 1.12.7