I haven’t felt anything getting warmer when we mix baking soda and vinegar, and on the contrary, when measuring the temperature of the liquid in the jar, it goes down by 5-6 degrees. Is the temperature falling inside the liquid itself evidence of heat being released?
There is nothing like experimental data to get at the truth.
You have discovered an error in the text. The baking soda-vinegar reaction is endergonic. That is, heat from the environment is sufficient to drive the reaction. As heat from the environment goes into the reaction, the temperature falls.
Congratulations and thank you for exposing this error in the text.