Flask Redirect loosing form data

Question

I am new to Flask. I have a simple page which takes some inputs & redirect to same page with inputs displayed this works fine with render template method but I want to avoid this as with every refresh it asks for resubmission so I am trying with redirect url_for method , the page gets redirected successfully but form data is not available. How can I fix this?

from flask import Flask, render_template, request, redirect, url_for
app = Flask(__name__)

@app.route('/', methods=['GET', 'POST'])
def index():
    if request.method == 'POST':
        form_data = request.form
        print(len(form_data))
      
        return render_template('index.html',form_data=form_data) # this works
        # return redirect(url_for('index',form_data=form_data))  this doesn't work
    return render_template('index.html',form_data=[])


if __name__ == '__main__':
    app.run(host='127.0.0.1', port=8000, debug=True)

html

<form action="" method="POST">
  <label for="cars" class="form-label">Select Employee Name</label>

  <select name="Employee Name" id="Employee Name" required class="form-control">
    <option value="none" selected disabled hidden>Select Employee Name</option>
    <option value="saab">Saab</option>
    <option value="mercedes">John</option>
    <option value="audi">mark</option>
  </select>
  <label for="submission Date" class="form-label">Select Submission Date</label>
  <input id="submission Date" type="date" name="Submission Date" class="form-control" required />

  <label for="Submission Status" class="form-label">Select Submission Status</label>

  <select name="Submission Status" id="Submission Status" required class="form-control">
    <option value="volvo">Pending</option>
    <option value="saab">Submitted</option>

  </select>
  <button type="submit" class="btn btn-primary form-control m-2">
                        Login
                    </button>
</form>

<div>
  {{form_data}} {% if form_data|length
  <=0 %} {{form_data}} {% else %} {% for x,y in form_data.items() %} <h1>{{x}}{{y}}</h1>
    {% endfor %} {% endif %}


</div>