Yes, he did.

That's all I can say without seeing a picture.

here it is, it didn't upload the first time

I don't think that style has a backdraft damper. Unless he installed one on it which is entirely possible. You should ask him if there is a backdraft damper installed with your roof cap. Such a damper allows air out (when your hood is turned on) and closes after to keep outside air from coming in when your range vent is not on. Without it, it's like an open window all year, cold air can come in during winter, hot during summer... along with other things.

I'm not sure what 'correct' means in this context, but I might have used something different.

something like this

Yes, the cap is tilted. My main concern is that I'm not getting a lot of suction from my hood and I'm wondering if the cap type could affect that-been trying to weed out all the variables that could impact suction. Appreciate all the comments and suggestions!

How long is the run of pipe between the hood and vent? How many elbows are there?

In addition to the questions Isaac asked, please tell us the cfms of your hood, and the exhaust duct diameter (6”, 8”?). Those will have a big effect on how strong the suction is.

Total run is about 15'. It runs straight up from the hood, through the second floor and the attic with no bends. Duct diameter is 8". Hood has max power of 1200 CFM. Thanks!

A rated volumetric flow rate is never achieved in practice because it is measured with the blower effectively operating by itself outside.

8-inch duct is a bit small for even the likely flow rate of 800 CFM (given plausible pressure losses and typical fan curves). [This comment is directed toward normal blower designs; VaH blowers are more sensitive to pressure loss]

Also, worth checking is whether any dampers that are installed are free to open, or have been accidentally inhibited by errant sheet metal screws.

I don't think that style of cap is intended for a range hood. You need one like Weedmeister linked to.

Within the last couple of months, someone else posted who had a dryer vent with a cap the same style as the one you have. Complaint was that it took a long time, like 3-4 hours, to dry a load of clothes.

That style of cap is about the cheapest vent cap you can buy...which may be why your contractor bought that one instead of one that is intended for a range hood.