The most recent MBPs were being throttled after mere seconds of 100% CPU due to the poor heat management and poor fan profiles; Linus Tech Tips was able to go from sealed box to throttled CPU in under 20 minutes without even trying. A firmware update to address the fan profile issue improved this but it still has issues.
The MBPs were not really designed to handle the heat of an i9
The MBPs were not really designed to handle the heat of an i9