It depends how aggressively your reformatter changes your code. For example, Prettier will take this JavaScript line:

  document.addEventListener('keydown', e => { console.log(e) });

and convert it to this, which changes both whitespace and syntax:

  document.addEventListener("keydown", (e) => {
    console.log(e);
  });

I don't think there are any diff tools that can hide the differences there, even though they're superficial.

[0] https://prettier.io/