How to replace underscores with spaces?

You can replace all underscores in a string with a space like so:

str.replace(/_/g, ' ');

So just do that before the content is put in. If you need to perform the replacement afterwards, loop using each:

$('.name').each(function () {
    this.textContent = this.textContent.replace(/_/g, ' ');
});

ES2021 introduced the nifty replaceAll()-function which means it can be written as:

str.replaceAll('_', ' ')

If you want to do multiple elements just loop over them and use forEach():

const elements = document.querySelectorAll('.name')   
elements.forEach(e => e.innerText = e.innerText.replaceAll('_', ' '))