Looks totally illegal and bush league to me. You WILL get birds nesting inside it like that. It should have a termination kit like a fireplace.
We don't sidewall vent our furnaces but Lennox should have a approved kit for it and their dealers can get it.
That looks totally illegal and is prone to vandalism. Kids can turn that elbow up and rain will get in. No way has that met the code. I doubt these guys even check with Lennox and this dude just slapped it out like that.
There were a few 80% efficient furnaces side wall vented where I am. York had the Concept 2000 in the 80's and I believe Olsen had one. I did not like the termination kit as the fumes could stain the stucco or siding but they were legal. The inducer has some power and as long as the pressure switch in the furnace is proven then it is safe to use.
Also, that termination is a code violation. B-vent requires a 1" clearance to combustibles. Your vinyl siding is combustible, let alone any framing under it within 1" of the B vent.
Next, B-vent is for negative pressure draft systems only. So even if your furnace were to be approved for side wall venting, B vent is not the proper type of vent pipe to use.
The York etc., used a stainless flex pipe and not B-vent. B vent is not airtight.
A sidewall power venter can be installed.
The venter gets installed on the wall, and the B-vent ran to it. The venter makes the flue negative pressure again. The venter is wired up to interlock with the furnace, meaning that if the venter fails, the furnace won't run. At least not in heat mode.
Call the gas company or whoever does your gas inspections and have them look at it as local codes can be different that national ones.