Sinkage in the middle of my loaf once baked

I curious as to why the recipe uses baking soda and not baking powder. Pumpkin is an alkaline food. There does not seem to be an acidic ingredient to create the leavening. Usually with banana bread, there's brown sugar which is acidic, so the baking soda makes sense there. Is it suppose to be baking powder? If it is baking soda, could there be too much of it? I've had cake sink in the middle because there was too much leavening.

I've also noticed this depending on the oven I'm baking in, ie. if I bake it at a friend's house or an Airbnb kitchen, it might take longer to bake. It can help to bake until a wooden skewer or cake tester in the middle comes out clean!

Chey - you're right, old or inactive baking soda can cause breads to either not rise or sink. You've eliminated that possible cause with your new box.
Here is an article with more ideas - too moist flour, opening the oven door, etc.
Have a look and see if any of them may apply to your situation.
The article is technically about banana bread, but I apply their rules and cautions to all sweet breads with recipes like banana bread.
Good luck and I hope you fix the problem!
https://breaddad.com/why-does-my-banana-bread-sink-in-the-middle/#:~:text=Moisture%2Dcontaminated%20flour%20can%20add,in%20a%20banana%20bread%20sinking.