Mozzila returns an empty list, why?

Question

Mozilla Firefox

It works fine in all browsers, the mozilla returns empty (Brought
the function to the most dry form)

const muFunc = data =>{
let catalog = [{id: 229, level: "bla bla"},{id: 239, level: "bla bla"}]
let arr = catalog.filter(x=>x['level'] === data)
console.log('list', arr) // arr = []
}

let dataTest = 'bla bla'
muFunc(dataTest )

What's wrong with her?