From my understanding it's a motherboard layout/cooling issue. Not going to fix that with software.

Definitely possible to limit the wattage received on that side in firmware.

I haven't heard of any change; my own setup is on the right. I will say that the corner of my computer where power is plugged in is uncomfortably hot.

Is it closed ?

Because I've had my MBP plugged in for the last 6 months, driving 2 external 4K displays on one side, power-in on the other, and an OWC 10Gigabit dock in the last port.

It's cool to touch, but I have the lid open (I use the LCD as the third display). I've read of people saying it gets hot when the lid is closed...

Nope, it's open; I use it as a second monitor as well. It's also on a stand (Roost) that exposes probably 99% of the bottom of the computer to air as well. 2019 Macbook Pro 16".

This is while the computer is under load (a Google Meet in Chrome, which is a power hungry little SOB). Also, the power is the only thing in the hot corner.

If it's always plugged in, then you're not charging the battery and there is less heat generated. I only have issues when it's charging the battery (maybe the battery controller is over there?)