Hi,
In mojoPortal 2.3.7.0 we added support for logging to the database, and in doing that, we wanted to capture a few things like ip address current thread culture, and the current url into separate fields whereas previously we were just appending them into the message field.
So what you are seeing there is nulls for application start and end events for those fields because no request is associated with those events, therefore there are not values for those fields for these specific events. For other events you will see values there.
As far as seeing less noise in the log, I have no idea, nothing changed in terms of what we log only how we log it. I have not seen any reduction of noise in my logs.
Hope that helps,
Joe