First if 'service-public.fr' still mandate a big tech browser (aka javascript) and does not have a noscript/basic (x)html portal/compatibility, it should go to

First if 'service-public.fr' still mandate a big tech browser (aka javascript) and does not have a noscript/basic (x)html portal/compatibility, it should go to hell, really. 90% of their activity is keeping the portals safe and available: it is extremely hard for "juicy" web portals, usually you need special handling from state grade internet carriers (don't be fooled this is not a "small" thing, and you better know how to do that yourself, or Big Tech will take it all away and will dictate everything to your own core network/telecom infrastructure). Second, I don't really know that piece of software, but if it is GPLv2, Orange should have provided the modified source code to the french administration (the "user"). If there was an "affero" clause, the french adminitration would have to publish to the french people the modified source code (or point to "upstream" if using verbatim). If you want to screw your "clients" with open source: use massive and complex (SDK included, for instance using c++/rust/similar) open source software breaking it sufficiently often to force planned obsolescence (ISO+feature creeps is about 5-10 years planned obsolescence cycle), you know, what we actually today...