Two openings from inside basement to outside and not sure of the purpose

Until you said it was only 12 years old, I was going to say coal chutes for an old coal furnace. I had those in an old house built in 1910. The chutes led to a walled area near the furnace chimney (the furnace was long gone but the chimney remained because it formed part of a wall in the kitchen). The walled area was filled with dirt when I bought it, but I excavated the dirt to try to make the space useable and found it to be half full of old coal. I put an ad in the paper and someone bought it from me and removed it.

Any chance your 12 year old home was built on the foundation of a 100+ year old home?

My next guess would be vent fan ducts for a radon extraction system, the flap would be to keep pests from going in but let the air our when the fan runs.

One possibility is that these were the inlet and outlet ducts for a heat recovery ventilator (HRV) that has subsequently been removed. An HRV is a sort of air-to-air heat exchanger that allows you to vent inside air to the outside, while drawing in fresh air from outside. The outgoing air exchanges heat with the incoming air so you get fresh air without needing more heating (in winter), or cooling (in summer). There would also be two missing connections to your furnace ducting.

An HRV is required by modern building codes in many jurisdictions, so it would not be surprising if a 12 year old house didn't originally have one.

If you're in a subdivision of homes built at the same time, check with your neighbors.