I have observed a strange phenomenon. I my mouth is very sensitive to very hot liquids (like, freshly made tea, or just freshly boiled water), so when I make my tea, I usually wait around 20 minutes before drinking it.
I am also a fan of a particular 3 in 1 instant coffee (3 in 1 meaning instant coffe + instant milk + sugar). I am taking one pack of mentioned coffee (21 grams in one package), pouring it with with freshly boiled water, mixing the coffee with water using a teaspoon in room-temperatured cup, then I am going to the toilet for ~5-7 minutes. When I come back from the toilet, my coffee is ready to drink. It is hottish, but I can drink it right away.
Later on (2-3 hours later), I am making a cup of tea, using the same cup, which is in the room temperature again. I am pouring two teabags (4 grams of tea) with the same amount of freshly boiled water, and I make my breakfast. It usually takes me around 10 minutes to make my breakfast, and when I am trying to drink my tea right after finishing making by breakfast, it is still hot as hell. I am usually waiting another 10 minutes, then the tea is still hotter than the coffee after 7 minutes, but it starts being acceptable for my sensitive mouth.
I have even bought a food thermometer to check the cooling speed of both liquids, but because of the coronavirus outbreak it hasn't arrived yet, but my "internal" thermometer - my lips, and isides of my mouth cannot be wrong. I can drink the coffee after ~7 minutes, and the tea after ~20.
I would understand a little change in cooling time, cause we are talking about 21 grams of instant coffee-sugar-powdered mix, the liquid is a bit densier, maybe there is more energy used to dissolve the coffee ingredients, the instant milk contains fat, but still - i am talking here about 13 minutes of difference between the time when my mouth can accept the temperature of both liquids, and we have to remember that the tea is still a hotter 20 minutes after I pour it with boiling water than the coffee 7 minutes, but it is drinkable.
Is there an explaination for this?