This keyword in the object

Question

I am new to Javascript and trying to understand arrow functions' this in the object.

1. const obj = {
    name:"Lia",
    sayHi: ()=> {
     return this.name
    }
   }
   

2. const obj2  ={
       age:"40",
       nested :{
           age: 50,
           named : ()=>{
               console.log(this, "arr")
               console.log(this.age)
               let x = ()=>{
                   console.log(this, "this")
                   console.log(this.age, "Age from nest")
               }
              x()
           }
       }
   }
   

On Google I have read that the arrow functions don't bind their own scope, but inherit it from the parent one. The parent in the first example is obj object. However, when I run the code, it prints undefined, meanwhile in the second example it works fine. Why? How can I know who is the parent of the this keyword in the arrow functions?