<input type="email" class="form__field" placeholder="Username or email" name="login_form[username]" id="login_form[username]" value="email" required />
<input type="email" class="form__field" placeholder="Username or email" name="login_form[password]" id="login_form[username]" value="email" required />
let $data = new FormData($(this).get(0));
$.ajax({
url: "form.php",
type: "POST",
data: $data,
dataType: "JSON",
processData: false,
contentType: false,
cache: false,
async: true
});