My iPad air4 gets hot while charging?

It is not unusual for an iPad to become warm when being used or charged - more so when using some types of iPad case. High screen brightness and/or CPU intensive Apps will also create more heat.

The key point is that whilst your iPad may become very warm in normal use or while charging, the iPad should not become uncomfortably hot to handle. If your iPad is becoming too hot to hold, you should take your iPad along to the Genius Bar at your local Apple Store - where the technicians can examine and test your iPad for faults.