I use a pi4 4gb as my controller for my ubiquiti device and as a pi-hole. It has the PoE hat with the fan removed and a piece of aluminium tube filled with coins and thermal goo standing on the processor. It is in a hot room (about 32c) and even under stress on all cores I have never seen higher temps than 67c.

The usb chip is hot as F though, even with updated firmware.