If the temperature of the container holding a chemical reaction drops, what is happening at a fundamental level?

Answer

The reaction is running a deficit and borrowing heat energy from the surroundings.

A temperature drop in the environment signifies that the reaction is endothermic, meaning it is consuming thermal energy from whatever it is touching to cover its net energy cost.

If the temperature of the container holding a chemical reaction drops, what is happening at a fundamental level?
chemicalenergyreactionendothermic