iPhone 13 touch screen irresponsive when plugged in the charger (20W)

My iPhone 13 touch screen became irresponsive (does not scroll continuously and doesn’t always click when tapping stuff) when plugged in the charger (20W) and laid down on a flat surface. As soon as i remove it from the charger or hold it up with my hand, the touch screen responsiveness gets back to normal. Any idea why this is happening ?

i just bought my iPhone a few days ago, do you think I should return it back while I can?