Yeah the right side isn't firing or may have a coolant leak. That "design" is known as piston wash. You can see the design of the ports and. How the fresh air fuel charge washes away carbon. Now with the right side, you can see there's no carbon. Coolant is very good piston cleaner. As well as un-burnt fuel.
I can't make out what's on the back of the left piston. But your defiantly not firing on the right side for one reason or another.