Why is my Dodge Durango leaking oil?

Without much detail as to what was done prior, anything we can offer here will be limited. That said, you can do a few things to get an idea. The first thing I have always done on Hyundai/Kia and FCA/Stallantis engines is I will take a few spark plugs out and check for oil consumption; granted the FCA/Stallantis vehicles that don't have Fiat engines aren't as prone to it (see: Jeep Renegade for something with the problematic Fiat engines), but it happens on these due to some cost-cutting on the Stallantis era FCA vehicles. You do not need a fancy borescope camera -- something like this will do the job. If you see oil on the spark plugs, that's a dead giveaway symptom it's burning oil.

You also want to check the valve cover gasket and the oil pan gasket. The one I usually check first is under the engine bay since it's plain as day once you take the beauty cover off. For the lower pan, jack the car up and check around the pan. The oil pan one is pretty easy, and you can usually get replacement gaskets for $10-20. Sometimes, the manufacturers use a high-temperature gasket maker at the factory, in which case, you will need the high-temperature variant if you need to "reseal" the pan due to the gasket maker failing (make sure you scrape the old gasket material off with a blade before putting new material on, and DO NOT GET IT IN BOLT HOLES!). The valve cover part can be purchased at any auto parts store or online, but you need to search based on the engine code in your Durango.