Self-Harm
The combat carriers possessed the capability to descend from orbit and land on any planet with a standard amount of gravity. That did not mean they did it all the time. Any ship that landed on a planet became a sitting duck. Therefore, the Vesian combat carriers remained in orbit and instead sent out smaller transport ships that conveyed the mechs to the surface.
One peculiar nature about Cloudy Curtain was its ever-present cloud cover. The clouds not only blocked vision, but various other signals as well, so the Vesians wouldn't be able to coordinate between their space and ground forces very well.
However, this did not hinder their operations too much, as Cloudy Curtain itself hosted numerous quantum entanglement nodes that maintained contact with the wider galaxy, which could all be hacked in many ways. The Vesians also deployed floating comm buoys to maintain secure lines of communication.