iPhone 12 Pro Max heats up with Fast Charging

My iPhone 12 Pro Max never heated up before whenever it's charging, only a little warmth on the back, I was using a 5W adapter then. But when I switched to the 20W power adapter, I noticed a heat buildup on the back, just below the cameras. It does charges really fast and the heat is tolerable to touch, but it's alarming. Is this a normal occurrence during fast charging?