The 2018 MBP’s had major overheating issues. I have one that was late 2018, after they’d supposedly fixed the issue. Only time the fan really kicks in for me is playing Civilization V through Steam. My understanding is that when the CPU overheats (basically why the fan kicks in) it also drops the processing speed. Which then triggers a recursive loop.
Intels have always had overheating problems. It’s probably why Apple abandoned Intel and moved to Apple Silicon.
