Why STM32H745xxx can't run at 480Mhz when the core is supplied by internal SMPS directly?

I know that.

Because the volatage for the core actual needed is 1.38V. The internal SMPS output voltage is too big.

It will make IC more heater.

As to,why internal LDO can run at 480Mhz, in my opinion, it is that the LDO area of the chip can bear higher temperature.