GTK client 8.0 does not launch LibO for reports

Hello everybody,
on my ubuntu 26 machine, I have installed:

$ flatpak list | grep -i tryton
Tryton 7.0	org.tryton.Tryton-70	7.0.40	stable	system
Tryton 8.0	org.tryton.Tryton-80	8.0.5	stable	system

With the 8.0 flatpak client, no odt report will be opened, no invoice, pick list, sale, whatever. No problem with the 7.0 flatpak, and no problem with the 8.0 pip client.
I can deal with the pip client, so no problem for me - but maybe somebody is interested.

EG