People like Gamer Nexus has a track record for testing PC components.
Now look at Austin Evans videos and tell me if his track record is good at testing PC components.
Both PS5 chips produces the same heat because the heat they produce are tied to power draw and not frequency. If the exhaust heat is higher than the old model and fan speed is lower, it means heat transfer from the chip is better.
It's the fan speed that determines how hot the the internal temperature of consoles/PCs is, not exhaust heat.
Also, a larger heatsink maybe less efficient if it doesn't have proper airflow. You start to get diminishing returns if the air can't flow through all the fins fast enough. Which is my guess why Sony reduced the fin stack at the bottom left.
Gamer Nexus did a airflow test that shows the airflow of the PS5 is mostly in the middle.
Now when you look at both heatsinks you can see the redesign heatsink looks more balanced in terms of airflow through all fins.
As for all the copper that was removed, was it really needed?
Take a look at GPU heatsinks. They don't have all that copper cold plate, just needs enough to cover the chip itself.
To say the PS5 has a worst cooling doesn't make much sense. Especially when it still uses liquid metal and the fan doesn't ramp up.