Flask + sqlite + html

Question

I need to make that when I click register on the site, the data is added as a new line in the database. But when the button is clicked, the site is simply updated, how to fix it? I tried to rewrite many times, because of my little knowledge of languages, nothing really worked out.Here is the python, html and css code

from flask import Flask, render_template, request, render_template_string, url_for

app = Flask(__name__)
z = -1
conn = sqlite3.connect(r'C:\Users\Иван\Desktop\Новая папка (2)\database.db', check_same_thread=False)
cur = conn.cursor()
cur.execute("""CREATE TABLE IF NOT EXISTS passwords(
   id TEXT PRIMARY KEY,
   login TEXT,
   email TEXT,
   password TEXT);
""")
conn.commit()

def search_in_db(login,email,password):
    data = (login,email,password)
    cur.execute("INSERT INTO passwords VALUES (?,?,?)", data)
    data_1 = cur.execute(f"SELECT * FROM passwords;").fetchall()
    return data_1

@app.route('/reg', methods=['POST', 'GET'])
def reg():
    return render_template("signup.html")
def loop():
    print(cur.execute("SELECT * FROM passwords").fetchall())
    if request.method:
        site = list(request.form)
        for i in site:
            if i == 'reg':
                a = request.form['log']
                b = request.form['email']
                c = request.form['pass']
                db_table_val(a, b, c)

        data = search_in_db(site)
        return render_template('index.html', message=list(data))
    else:
        return 'NOPE'
def db_table_val(log,email,passw):
    cur.execute('INSERT INTO passwords (log,email,passw) VALUES (?, ?, ?)',
                (log,email,passw))
    conn.commit()
@app.route('/')
def main():
    return 'haha'

app.run()

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
body {
    font-family: 'Roboto', sans-serif;
}
input {
    height: 45px;
    width: 100%;
    color: #3B5983;
    font-size: 14px;
    line-height: 16px;
    border: 2px solid #E9F2FF;
    border-radius: 5px;
    padding-left: 25px;
}
input:focus {
    outline: none;
    border: 2px solid #C1D9FD;
}
input:valid {
    border-color: greenyellow;
}
input:invalid {
    border-color: orange;
}
input:not(:focus):invalid {
    border-color: #C1D9FD;
}
main {
    background: #F1F5FE;
    height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}
.circle {
    position: absolute;
    z-index: 1;
    width: 2534px;
    height: 2534px;
    border-radius: 50%;
    background: #F7FAFF;
    box-shadow: 0px 4px 70px 6px rgba(217, 229, 255, 0.25);
    animation-name: fadeCircle;
    animation-duration: .7s;
    animation-timing-function: ease-in-out;
    animation-delay: .3s;
    animation-iteration-count: 1;
    animation-fill-mode: forwards;
}
@keyframes fadeCircle {
    0% {
        width: 2534px;
        height: 2534px;
    }
    25% {
        width: 2000px;
        height: 2000px;
    }
    50% {
        width: 1500px;
        height: 1500px;
    }
    75% {
        width: 1000px;
        height: 1000px;
    }
    100% {
        width: 534px;
        height: 534px;
    }
}
.register-form-container {
    opacity: 0;
    position: relative;
    z-index: 2;
    max-width: 415px;
    width: 100%;
    background: #FFFFFF;
    box-shadow: 0px 6px 50px rgba(217, 229, 255, 0.7);
    border-radius: 20px;
    padding-left: 30px;
    padding-right: 30px;
    padding-top: 38px;
    padding-bottom: 38px;
    animation-name: fadeForm;
    animation-duration: .7s;
    animation-timing-function: ease-in-out;
    animation-delay: 1.4s;
    animation-iteration-count: 1;
    animation-fill-mode: forwards;
}
@keyframes fadeForm {
    0% {
        opacity: 0;
    }
    25% {
        opacity: .25;
    }
    50% {
        opacity: .5;
    }
    75% {
        opacity: .75;
    }
    100% {
        opacity: 1;
    }
}
.form-title {
    color: #30507D;
    font-weight: 500;
    font-size: 20px;
    line-height: 23px;
    margin-bottom: 38px;
}
.form-field {
    margin-bottom: 13px;
}
.button {
    width: 100%;
    font-weight: bold;
    font-size: 14px;
    display:block;
    height: 45px;
    background: #247FFF;
    border-radius: 5px;
    color:#fff;
    text-transform: uppercase;
    text-align: center;
    line-height: 45px;
    cursor: pointer;
    border: none;
}
.button:hover {
    background-color: #0D6CF2;
}
a.button {
    text-decoration: none;
}
.button-google {
    color:#C6CFDC;
    background: #F2F6FF;
}
.button-google:hover {
    background: #E2E6F0;
    color: #fff;
}
.divider {
    font-weight: 500;
    font-size: 12px;
    line-height: 14px;
    color: #405D87;
    text-align: center;
    padding-top: 25px;
    padding-bottom: 25px;
}

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <link rel="preconnect" href="https://fonts.googleapis.com">
    <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
    <link href="https://fonts.googleapis.com/css2?family=Roboto:wght@700&display=swap" rel="stylesheet">
    <link rel="stylesheet" href="{{ url_for('static', filename='css/style.css') }}">
    <title>Форма регистрации</title>
</head>
<body>
    <main>
        <div class ='circle'></div>
        <div class='register-form-container'>
            <h1 class="form-title">
                Регистрация
            </h1>
            <div class="form-fields">
                <p>
                    <input class="form-title"  type="text" name="log" placeholder="Login">
                </p>
                <p>
                    <input class="form-title" type="email" name="email" placeholder="Email">
                </p>
                <p>
                    <input class="form-title" type="password" name="pass" placeholder="Password">
                </p>
            </div>
            <div class="form-buttons">
            <form action="" method="post">
                <p>
                    <input class ="button" type="submit" placeholder="Sign Up" name="reg">
                </p>
            </form>
                <div class="divider">или</div>
                <a class="button">Google</a>
            </div>
        </div>
    </main>
</body>
</html>