UDON DUNGEON․（ 拷問部屋跡。）passcode

https://www.vrchat.com/home/world/wrld_d7d54c59-4119-4511-bcaa-c623f55e6999 

The password as soon as you enter the birdhouse is "0343".

The next keypad you see when you squat at the entrance is "5777". 

It appears when you take a prone position next to Qvpen.