Possible Top end or VVT replacement required? 75dB+ knocking from engine top end - 2018 - Nissan Pathfinder

Question

First the link Hello, I have a 2018 pathfinder with a reasonably loud (i'm estimating it at over 75dB standing about a meter back from the front of the vehicle). The sound seems to be coming from the part of the engine where the crankshaft meets up with the driveline. Please forgive my looseness with terms, I am certainly no expert on cars. My first thought was that it sounded like valve knocking (again, not an expert but just a thought) but the point at which the sound seems to be eminating is not the top end but more what i think is the timing chain. I recorded a video yesterday while the car was hot (it was 40C at least out and the car just came home from a long drive). The noise increases with heat, which in my opinion is typical for just about anything that makes noise. The mechanic at nissan had a listen and believes that my engine needs to be rebuilt and VVT system replaced. They are ballparking the T&L at $5000CAD. Shortly after that I took the car for an oil change. The temperature dropped dramatically tonight. It is now around 16°C. I've just started the car and the knocking is completely gone. The car is running tickity boo as we call it. Any thoughts on this sound. I have attached a videio