“Method Not Allowed” error in Flask after submitting form data

Solution
@app.route('/', methods=["GET", "POST"])
def home():
    return render_template("home.html")

@app.route('/register', methods=["GET", "POST"])
def register():
    
    
    if request.method == "POST":
#        data = {}
        name = request.form['name']
        place = request.form['place']
        descr = request.form['descr']
        email = request.form['email']
        collection.insert_one({'name': name, 'place': place, 'email': email, 'descr': descr})
           
    
    return render_template("register.html")

COMPLAINT FORM