Ivy Bridge did actually run hotter die temperatures than Sandybridge. Part of that was their unfortunate decision to replace solder with thermal paste, between the die and IHS. Another part of it was due to the size reduction of Ivy Bridge's cores. Smaller cores need to have proportionately smaller TDPs, or else the amount of thermal energy per unit of area goes up.
The era of constant thermal density ended approximately in 2006, so it's a given that a lithographic shrink of effectively the same microarchitecture would run at higher thermal density. And that can result in hotspots that are more difficult to cool.
This is one reason Zen 4 is thought to run rather hot, in fact - the thermal density with TSMC's N5 node is quite high. So, given these CPUs' use of Intel's 20A node (and 18A, for Panther Lake?), it seems to me like it might be more of a
necessity to tolerate higher TJMax temperatures.