In React the submit is yours, which is both the problem and the fix.

export function ContactForm() {
  const [state, setState] = useState({ status: "idle", message: "" });

  async function handleSubmit(event) {
    event.preventDefault();
    setState({ status: "sending", message: "" });

    const form = event.currentTarget;
    const response = await fetch("https://freelyform.com/f/FORM_ID", {
      method: "POST",
      headers: { Accept: "application/json" },
      body: new FormData(form),
    });
    const result = await response.json().catch(() => ({}));

    if (response.ok && result.ok) {
      form.reset();
      setState({ status: "sent", message: result.message });
      if (result.redirect) window.location.assign(result.redirect);
    } else {
      setState({ status: "error", message: result.message || "That did not send." });
    }
  }

  return (
    <form onSubmit={handleSubmit}>
      <label htmlFor="email">Email</label>
      <input id="email" name="email" type="email" required />
      <label htmlFor="message">Message</label>
      <textarea id="message" name="message" required />
      <button type="submit" disabled={state.status === "sending"}>
        {state.status === "sending" ? "Sending…" : "Send"}
      </button>
      <p role="status">{state.message}</p>
    </form>
  );
}