[diro]

Every case can be different...
We are discussing options what it can be. In most cases dpf is a reason.
Personally I would monitor live data but not everyone is capable to that
Critical data in such scenarios is dpf differential pressure readings, exhaust temperatures, oil pressure, status of dpf filter.
Very important figure is exhaust temperature which is about 150 - 200C. Sometimes a little higher. It depends on the driving style.
having even a little dpf clogging exhaust temperatures will be higher and it may cause high oil consumption. Condition of the engine and its components matters.
Thinner oil can be a factor too.
If you are a Greenpeace member - ignore my advice to delete dpf

As I mentioned before previous DPF issues could be a reason car has oil consumption problems now. With DPF fitted is more guessing than seeing an obvious fault.
A massive oil consumption also very likely is a consequences of the previous DPF issues when the harm to the engine been done

In my opinion to start solving such problems you need to delete DPF (it also has to be gutted). Than it will be more clear what comes out from the exhaust how car's performance changes etc.