Had you used defrost setting before? The non defrost setting is just cabin heating/cooling, the same as you may set on a hot day when you wanted to cool the cabin. Its not a defrost so no reason why the defrost mechanisms such as the cabin camera housing would need to be operational. I can't remember about rear window heater if that gets triggered as tbh, except in hot temperature I don't use the cabin temperature controls remotely. The door mirrors are triggered by rear windscreen heating. Prior to 2021.40.6, even defrost setting wouldn't trigger the front camera element. Sentry will trigger front camera defrost and was the method needed prior to 2021.40.6 - some reports of seat heater also triggering it. The camera heater wires do not get hot, but mildly warm. Once on, that area will clear pretty quick. My test this morning was 8 minutes between turning on and checking, but in the past, even after 4 minutes I have seen the camera area be clear and I suspect its even quicker than that. No reason why front window would clear the camera area as the top of that area remains frozen, although does benefit from a little heat from the cameras themselves - the tell tell is usually the outside top/side of the passenger side windscreen which has the camera heater wire running along it so will often show a decidedly marked line if the camera element has been on - not so obvious in todays picture but very clear in the image
in this post.
Anyway, looks like it hasn't regressed in v11 (yet) which is good news. It wouldn't have surprised me if it had.
As for car like a sauna, if you defrost first, then when cabin gets to temperature, if you turn off defrost at that point but keep cabin temperature on, then the cabin will have had a chance to cool (especially if passengers open other doors and leave them open) plus you can then let the car remain at normal setting as if you specifically turn it off in the app, it will also turn it off in the car. As the cabin temperature sensor is pretty much in the cabin heater air flow it vastly over reads the cabin ambient so even though cabin may say 29C, that's only the inbound air flow and pretty quickly cabin temperature will read much lower, possibly not even the temperature set point.