EDF has recently been re-nationalized, and has always been under strong government influence. It's not a good example of a civilian/free market nuclear power plant operator.
I really doubt ARENH is the problem because as far as I understand it, it only applies to EDF's existing nuclear power plants. At 42 EUR/MWh wholesale, those plants should still make a tidy profit. Apparently, too few of them were actually running last year, and the French government imposed further price restrictions that also affected resale of energy that EDF purchased elsewhere at market prices (not coming from EDF's own nuclear fleet or its other power plants).