Severe ringing when high side MOSFET in half bridge circuit switches on
Try probing on the power supply rail. I bet you see those spikes on there. It'll be due to the lead length between your bench supply and the MOSFETs. Clearly you won't see it on the lower FET side because your scope is referenced to that rail but, if you probed back at the power supply I bet you would.

Try a 1uF or 10uF ceramic across the power rails close the MOSFETs.