Because he's a puppy and that's what they all do when bored, full of energy, and when left alone with no guidance!
Most of us in the USA crate train to help with this. Hard for us to train and prevent something when we aren't home. So nice to KNOW when I come home that I arrive full of love for my puppy knowing they are safe and didn't destroy anything, rather then arriving home and bracing myself for the mess.
There is something about wood that some young dogs, like your 8 month old, and pups love to chew on. I would try one of those sprays like bitter apple - it shouldn't hurt the cupboards and Jake hopefully will find the taste too awful to keep chewing on them and will then go back to his own chew toys.
Lol I think was boredom tbh It was during the night ive tried kongs as well hes threw them in 5 mins lol any ideas hes geting alot exercise to be fair but hes into everything he just cant chill when he g9es out he barks at the wing the rain and plastic bags lol