Ive never seen that before and I know that the QHY9M has a dual sealed chamber set up. The primary chamber is around the sensor itself is fully sealed, the secondary chamber isn't so sealed but like Marc said they provide 2 options, dry air nipple to circulate dry air though the secondary chamber and a desiccant plug. There is also a inbuilt heater.
The only time I had a icing issue was before i kept the qhy9 in a pelican case with rechargeable desiccant packs. I've had it in the fridge just recently to do -35 and -40 deg darks for a upcoming trip where i know the ambient temp will be around the 0 deg mark. There wasn't a frosting issue in sight and it was at those temperatures for 3 days in the fridge.
All in all the qhy's are a great for beginners using high end chips and offering great features. Yes they need to work on their drivers, but in my case i have no issues as i have the original drivers... if it aint broke don't fix!
there is very little in the astro world that doesn't require lots of love to make it work properly unless you spend $$$ and then everything is already done for you.
