That furnace has a knock out why did they chop it all up like that I would sure recommend a new door you paid good money and you should be pleased at end of job. Make them get you a new door. And make them only use the knock out for the side no need to make hole any bigger than the knock out.
You guys are splitting hairs here. Carrier should've been hit in the head when they designed these doors to begin with.
I'd be more concerned about the fact I got myself a cheap 80% furnace.
I agree I am not a fan eitherof this design at all to me it looks cheap and the doors hardly match up when putting it back on they really don't give you much room with the b vent inside the furnace. I was installing a down flow 80% went out the side like that what a pain it was. But I never had to chop up the knock out like that admitting it is pain in the ***.