this is undefined inside a normal async function (not arrow function)

Question

This is something that should definitely work and I don't get why it doesn't:

mounted(){ //in object literal
    console.log(this) //prints out the object
    var jq = require('jquery')
    jq(window).scroll(async function() {
        console.log(this) //prints undefined
    })
}

I know that if I used async ()=>{console.log(this)} then it would definitely be undefined but I have no clue why it would be that while using an old-school function? Am I missing something?