Installing CT-4 vent for dryer – found 2 strange small holes – what are they and should they be blocked/covered?

I recently had a CT-4 vent installed to exhaust my dryer through my attic(it was the only way).

I turned on the dryer to test the connection and I felt some air blowing out. I found the culprit was 2 of these holes you can see in the image below.

My question is: are these hole supposed to be exposed? Im assuming no because I DO NOT want the humid dryer air into my attic.

Should these be covered with the dryer duct and sealed?

What is the reason for these 2 holes?