Sometimes…when the label is missing or missing key information, you are looking at a gray market appliance. Secondly, the flex connector should never pass through the cabinet wall regardless of how big the hole in the cabinet is. Things including s**t can happen and the flex connector can come into contact with the edges of the opening and bad mischief can follow, even if a few years later.
Here is the complete installation instructions.
My understanding is that a flexible connector is not allowed to pass through any housing. Is the large hole with the barcode and numbers on it supposed to be for combustion air? you could run the furnace and see if there is any exhaust coming from it also. just some thoughts on possibilities
Guess I should read the other replies first but I suggested it was combustion air and according to the document supplied, 101874004R is a combustion air orafice for the *G8SA-100U-T35C1 type air furnace.