Different carbon rings in one weekend
For the first time this season, Ferrari were using different ring types in their rear wheels during one single race weekend. As Carlos pointed out on the forum, both cars were fitted with the big rings as displayed in the image, while after the first race stint they were both fitted with smaller rings, in fact the specification of before the Turkish GP. Contrary to what Ferrari and the FIA state though, the device is certainly an aerodynamic help. While it is considered an allowed brake duct by the FIA, the ring itself is a burden to air hot air and dust coming out of the brake. Although it is possible for the FIA, it seems nearly impossible that the device lowers brake temperature. However, as rear brakes actually require less cooling, this duct may also be designed to decrease cooling and therefore keep the brakes warmer.
A very biased analysis. The reason for the Ferrari being slower could well be the tyres and the condition of the circuit. There is also no proof that Ferrari needed less/more cooling for the brakes. For more views on this check here.