Maybe not a proof that the Russian authorities are involved in price settings, but I do wonder if the operating costs are that much higher to operate into SVO than into FRA from ARN.

ARN-FRA = 760 miles while ARN-SVO = 762 miles

ARN-FRA in T is SEK435 + SEK215 (tax & fee) = SEK650
ARN-FRA in Q is SEK1665 + SEK215 = SEK1880

ARN-SVO in T is SEK905 + SEK283 (tax & fee) = SEK1188
ARN-SVO in Q is SEK2035 + SEK283 (tax&fee) = SEK2318

Funny enough the lowest price ARN-SVO is identical between SK and SU but that is rather common outside EU. The strange thing is that the price level for the cheapest tickets are that much higher compared to most of the other destinations SK operates within Europe. The better fare class the less difference compared to many other destinations.

SK trips originating in Russia, however, are significantly cheaper and the tax&fee is lower as well (SEK153). For example a S class ticket SVO-ARN is SEK2520+tax&fee while a S-class ticket ARN-SVO is SEK4770+tax&fee. But again SK has the same price as SU.