Why does flipping something seem to always require turning up the heat?

The issue is that the first time, the pan has been pre-heated, so you’re both absorbing heat already stored in the pan as well as trying to absorb heat coming from the burner.

If we assume that you pre-heated the pan for 5 minutes before putting the food in, if the pan had had perfect conductivity to the food and zero loss to the environment (which is basically impossible), you’re actually absorbing 10 minutes of heat in the 5 minutes the food was in contact with the pan.

Because the food is limiting the temperature of the pan in the spot it was in contact, as it tries to reach thermal equilibrium, the areas of the pan in contact with the food are going to be slightly cooler than those that aren’t in contact (assuming your burner is heating the pan evenly, which isn’t perfectly true, but is typically close enough).

And as I mentioned in my comment, liquids will hit their boiling point and can’t go beyond that until the finish evaporating. So if you still have moisture in the surface of the food, it can’t go beyond 100°C/212°F.

For this reason, when flipping food over, I try to flip it onto a section of the pan that had been empty. For items like a burrito, that may take up most of the pan, I may turn them 90 degrees, so at least the ends are using ‘new’ sections of the pan.