Turkish Airlines has been quite annoying with this issue, they've constantly kept raising the fuel surcharges, especially in business class, during the last 2-3 years, to the point where they're now one of the most expensive airlines out there to redeem miles with, while a couple of years ago they were one of the cheapest. The taxes and fees in economy for the same itinerary are less than half of those in business, which considering brasilian law makes no sense. The direct flight from GRU to IST faces the same issue (something like 61€ in economy and 169€ in business) when Lufthansa (mind you, flying via Germany!) has the same fixed price of 41€ for either class (GRU-IST).
This is most likely Turkish somehow slipping those extra surcharges through the redemption network
. (it would be interesting to see what the analysis looks like for this award ticket, the ita matrix shows a YR fee of 320,84€ for the revenue ticket, plus 1-2 more surcharges, which means they add the surcharges Turkish charges for both legs separately at 100%, so actually the award ticket is a but cheaper)