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It gets worse with Maks and SCTs. The closed design and large pieces of glass (mirror and corrector) make it difficult to cool down, or to maintain equilibrium if the temperature is falling quickly during the night (e.g. in winter). You can get tube currents because the air inside the OTA is at different temperatures at the top and bottom of the tube.
The vents in the Celestron Edge SCTs allow an add-on fan (e.g. TempEst) to circulate the air inside the OTA with so that it's all at the same temperature and this apparently results in a dramatic improvement to the image, even though the scope is not in equilibrium with its surroundings.
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