If the air coming out of the console is hotter than before, it doesn't mean the SoC and heatsink have higher temperatures, it means SoC and heatsink have lower temperatures since more of the heat is being pushed out of the console. Since the shape of the console and the fan have not changed, there is also no "smaller stream of air" coming out of it, which would be hotter than a "larger stream of air" with the same efficiency - as another person commented.
The only explanation with the data we have for now is that they tweaked the shape and placement of the heatsink to improve efficiency.
When I say efficiency, I mean better heat displacement (from inside of console to outside of console) for less cost. It costs less to produce, it has less of an environmental impact, it's uses less fuel and money to transport. Win/win
Sorry, but that's a misunderstanding of how thermal transfer works. Thermal transfer efficiency is reduced as the thermal delta between two media (such as an aluminium heatsink and air, or SoC and heatsink) diminishes. The closer in temperature the air and your heatsink, the less heat your heatsink will be able to give off (if they are the same temperature, no thermal transfer will occur). Conversely, this also means that in a scenario where you have a constant airflow and the same size heatsink, in order for the air coming off it to be hotter, you also need a hotter heatsink - if the heatsink and ambient air were both the same temperature, then the air coming off would stay the same.
For example, if your SoC is at 90°C at a given thermal output, your heatsink at 60°C and your ambient air at 20°C, you'll likely have very efficient thermal transfer across the whole chain, and your exhaust air is likely to be significantly warmer than the ambient temperature. If your heatsink instead ran at 80°C under the same conditions, that would lead to the exhaust air being hotter - but also the SoC temperature being more than 90°C under the same thermal load, as the thermal transfer efficiency between it and the heatsink would be significantly lower - it would be more difficult for the SoC to dump its heat into the heatsink, causing it to run hotter.
And what causes a hotter heatsink? A higher ratio of heat input to thermal mass and surface area. Of course, this isn't a scenario with the same heatsink, but a smaller heatsink exhausting hotter air. What that means is that you're concentrating the same thermal load as before into a smaller thermal mass (heatsink), increasing its temperature compared to the larger heatsink (assuming airflow is unchanged). This is great for transferring heat to air, as you increase the delta to ambient, improving thermal transfer due to the heatsink being hotter. But there's a downside: the same dynamic applies between your SoC and heatsink - the smaller the delta, the slower the thermal transfer. And given that the SoC is the heat source and will thus always be the hottest of the two, increasing heatsink temperatures lowers the delta between the SoC and heatsink, meaning the SoC at the same thermal load will run hotter, as it won't be able to dissipate its heat into the heatsink as efficiently as with the larger heatsink.
While thermodynamics get complicated very quickly, this is pretty simple, really. Assuming constant airflow and thermal load (SoC wattage):
Warmer exhaust air <- warmer heatsink <- warmer SoC
Increasing airflow, for example, would lower the exhaust air temperatures as it provides more thermal mass (air) to dissipate the heat from the heatsink into, spreading the same thermal energy into a larger volume of air, which will in turn lower the heatsink temperature. So, another way for the airflow temperatures to be higher is to have lower airflow - but airflow is unchanged. I assume that's what you're trying to say with the "larger/smaller stream of air" thing? I've been clear throughout every post written here that I'm assuming unchanged airflow. Which is why it's quite safe to assume that the PS5 SoC with this new cooler runs slightly hotter than previously.
So: a hotter exhaust temperature is indicative of a higher thermal delta between the heatsink and ambient air, which increases thermal transfer efficiency
in that specific part of the thermal transfer. But that isn't the only part! A hotter heatsink - necessary for that efficiency increase - also indicates
worse thermal transfer efficiency between the SoC and heatsink, causing SoC temperatures to rise (. Overall, then, this will cause worse cooling, as the point of the cooler is to cool the SoC, not to have a large delta between heatsink and air.
