HTML valid and semantic markup:

  <form action="https://formspree.io/[email protected]"
        method="POST">
     <input type="text" name="name">
     <input type="email" name="_replyto">
     <input type="submit" value="Send">
  </form>

Indirect FormData manipulation, misuse of `class`, ignorance of dataset:

  <form class="dv-add-oneto:profiles:details"> <input type="text" name="firstname" placeholder="Please enter your first name"><br> <input type="text" name="lastname" placeholder="Please enter your last name"><br> <input type="number" name="age" placeholder="Please enter your age"><br> <button type="submit">Submit</button></form>

Yep! Sounds good to me!