iPhone 12, heats up while it's on charge

Hi, I just bought iPhone 12 yesterday (Nov 7th), however, i noticed while charging the new iPhone heats up a lot, which never happened to my previous iphone 8, unsure what could be of the issue ? I am using the new 20w power adapter - USB-C, yet no difference in the temperature while the phone is being charge. Could the phone be defective by any chance ? Perhaps, need to replace the phone ?

I was under impression, newer phone, perhaps the functionality would be / should be better than the iPhone 8, three generation old, however, a bit disappointed.

Need advise, please, thank you.