I’ll see if I can find any supporting articles, but IIRC, it has to do with the fats being softer or more reactive with your taste buds at warmer temps.

Edit: it’s mostly pop sci articles, so maybe it’s BS but seems the fats and amino acids get locked in the proteins when cheese is cold. https://www.sciencefocus.com/the-human-body/melted-cheese-tastes-good