All I can do is speak for myself...my RTT, Smittybilt in the instructions suggest rain fly the tent needs to be "seasoned". Seasoning process is remove the mattress from the tent. Then remove the rain fly. Take a hose & water down the tent & rain fly. Let dry for 24 hrs & follow with another application of water & another 24 hrs dry time. What this does is pulls the fibers in the fabric together tighter as well as the stitching.
On Facebook overlander groups I see many complaints on this subject. Personally I never had any issues because I followed the instructions before I mounted my tent on the trailer tent rack. But I see many who openly said they never read the instructions "thinking it's straight forward install" they stated.
Another issue with RTT owning is condensation. Personally IMO anti condensation matt does work for the floor & mattress. Our sheets & mattress is moisture free. Walls & ceiling are other issues, the only solutions "I" found that works for Sally & I are opening the skylights up 1\4 open, & unzip the windows about 3". We found by doing this we have hardly any moisture clinging to our ceiling or walls of our RTT. I called Smittybilt about putting on a waterproofing solution on the tent. They did not recommend that & would not warrant the tent if problems happen. I'm saying again just for me & Smittybilt RTT's is that if following the instructions of seasoning the tent before use, the moisture problems wouldn't happen. I can honesty say Smittybilt was right on the seasoning of the tent. I've camp'd were sudden heavy down pours came w\o water wicking in anywhere in our RTT.