Where is the PCV located?

Hello, it is located on the right valve cover (passenger side). I will post the diagrams below.
Has the Check Engine Light on or been on recently?

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

I'll look and see if there are any Technical Service Bulletins on the subject, there may be another hose from the opposite side valve cover connecting the 2, I didn't see any in the diagrams, but they are not always 100% correct.
The PCV system is for crankcase pressure, if it is excessive, that can mean the piston rings are getting worn somewhat and you're getting too much blow-by pressure into the crankcase.

Well, the real issue with them is carbon build up from over the years, the crankcase pressure needs a place to go, so it's released into the intake to be burned through the PCV system, if it can't release that pressure, it will start pushing out other places, like the front main seal, rear main seal, etc. Make sure that the line that runs to the valve cover is clear too, do the Inspection sheet I posted up above (page 6 and 7). The line that attaches to the PCV valve gets carbon build up inside too. The valve only allows a certain metered amount of flow, so if it's too small of an amount of flow, it can cause issues, rough idle, stalling, etc. So, if you really should replace it if you're getting oil all the way into the intake air tube, Thats pretty extreme. The longer you wait, the worse things are going to get.
You don't want to end up getting carbon build up on the mass air flow sensor.

Here are the listed components below, they don't offer very detailed diagrams of it.

Does this model have a turbo charger? A fault in the turbo charge can cause oil to end up in the intake tube, excessive oil pressure being pushed into the valve cover area, there should be oil pushed up into the top end to lubricate the camshafts and components up there but too much oil will be drawn into the PCV system. Do you keep up with the oil changes on this car? If the oil changes are neglected buildup of carbon occurs and passages get clogged and that can cause high oil pressure in some areas and lower in others. Or even possible worn-down piston rings causing excessive blow by into the crankcase. Things like this are usually what cause oil in the intake tube.
You could try an oil additive to try and clean up and carbon deposits.
I see some models may have a turbo charger on them, but I'm not sure about your vehicle. I'm looking through the Bulletins to see if there's anything to check besides what's listed above. Here's some pictures of carbon build up issues due to lack of maintenance and oil changes. Really if there isn't a problem with a turbo or super charger type system, keeping up with the regular 30,000, 60,000, 90,000 mileage services is what you want to do, and keeping the oil changes regular, especially if you make long distance trips.
There is a Technical Service Bulletin on cylinder bore issues, this would cause excessive blow by on the piston rings into the crankcase. But I don't see anything exactly mentioning oil in the intake tube. So, it can really be caused by a lot of things or a combination of smaller issues.
I'd start with changing the PCV valve, get one from the dealership, they might have an updated part. If your car does have a turbo charger, you can get that checked out, make sure it's functioning correctly and there's no issues with it.
But with the way cars are built these days, keeping up with maintenance is a big deal. Making sure the correct type of oil is put in it. Technology has advanced so far now, especially with higher end vehicles like a Cadillac, they need extra care. A PCV valve that's too restrictive would cause the car to leak oil in other places, because the crankcase pressure would just start to push out of lower engine seals.

If it's a line going to the intake manifold, there will be vacuum there when the throttle plates are closed. Manifold vacuum drops when the throttle plates are opened. GM recommends not using any fuel or oil additives on these vehicles. Just using the proper oil listed in the owner's manual and keeping up with regular changes. Those additives can actually cause damage to certain parts of the engine. Mostly to seals because the additives are made to break up carbon build up so they're too strong and you can end up with premature oil leaks.
I didn't put the whole TSB down below because the rest is just about keeping tire pressures correct and things to do to improve gas mileage. Using cruise control, etc.