How to fix such error when checking pyTelegramBotAPI subscription?

Question

Python

Hello. I am making a Telegram bot on PyTelegramBotAPI in which there is a subscription check for a telegram channel and encountered this error:
If one person writes the /start command and immediately after it some other person writes this command, then the first person has the "Check subscription" button will simply stop working (it will simply write "Thank you for subscribing to the channel", but will not redirect to the valid function, which in turn adds a person to the bot's database). For the second person, the "Check Subscription" button will work properly.

Code:

Command handler /start

@bot.message_handler(commands=['start'])
def start(message):
    global usid
    usid = message.chat.id
    global usname
    usname = message.from_user.username
    try:
        global referrer_id
        referrer_id = message.text.split(' ')[1]
    except IndexError:
        referrer_id = 1005380696
    sql.execute(f"SELECT chatid FROM users WHERE chatid = '{usid}'")
    if sql.fetchone() is None:
        marku = types.InlineKeyboardMarkup(row_width=2)
        item1 = types.InlineKeyboardButton(" Проверить подписку", callback_data='sub_check')
        marku.add(item1)
        global res
        res = bot.send_message(message.chat.id, " <b>Добро пожаловать</b>\n\n❗ Для <b>продолжения работы</b> с ботом вам необходимо <b>подписаться</b> на наш <b>оффициальный канал</b>: \n\nhttps://t.me/*ссылка на канал*", parse_mode='html', reply_markup=marku)
    else:
        bot.send_message(message.chat.id, " Вы в главном меню.", reply_markup=mm)
        for value in sql.execute("SELECT * FROM users"):
            print(value)

"Check Subscription" button handler

@bot.callback_query_handler(func=lambda call: True)
def callback_inline(call):
    try:
        if call.message:
            if call.data == 'sub_check':
                user_id = call.message.chat.id
                group_id = "*айди группы*"
                check = bot.get_chat_member(group_id, user_id)
                if check.status == "member":
                    sql.execute(f"SELECT chatid FROM users WHERE chatid = '{usid}'")
                    if sql.fetchone() is None:
                        valid(call.message)
                        bot.send_message(call.message.chat.id, "✔ Благодарим вас за подписку на канал!\n\n❗ Если бот по каким-то причинам вам не отвечает - напишите /start.")
                        bot.delete_message(call.message.chat.id, res.message_id)
                    else:
                        bot.send_message(call.message.chat.id, "❗ Вы уже зарегистрированы.")
                elif check.status == "creator":
                    sql.execute(f"SELECT chatid FROM users WHERE chatid = '{usid}'")
                    if sql.fetchone() is None:
                        valid(call.message)
                        bot.send_message(call.message.chat.id, "✔ Благодарим вас за подписку на канал!")
                        bot.delete_message(call.message.chat.id, res.message_id)
                    else:
                        bot.send_message(call.message.chat.id, "❗ Вы уже зарегистрированы.")
                else:
                    bot.send_message(call.message.chat.id, "❌ Пожалуйста, проверьте подписаны ли вы на все каналы.")

The valid function to which the user should be redirected after validation

def valid(message):
    sql.execute(f"INSERT INTO users VALUES(?,?,?,?,?)", (usid, usname, 0, 0, referrer_id))
    for value in sql.execute(f"SELECT * FROM users WHERE chatid = '{message.chat.id}'"):
        print(f"Новый пользователь: @{value[1]}, referal: {value[4]}")
        for value in sql.execute(f"SELECT * FROM users WHERE chatid = '{value[4]}'"):
            print(value[1])
            ref_balance = value[2]
            print(ref_balance, value[1])
            new_ref_balance = ref_balance + 2
            print(new_ref_balance, value[1])
            ref_count = value[3]
            new_ref_count = ref_count + 1
            print(new_ref_count, value[1])
            bot.send_message(value[0],
                             f"➕ Вы пригласили <b>реферала</b>.\n\n Текущий баланс: <b>{new_ref_balance} рублей</b>\n\n Всего приглашено пользователей: <b>{new_ref_count}</b>",
                             parse_mode='html')
            sql.execute(f"UPDATE users SET balance = {new_ref_balance} WHERE chatid = '{value[0]}'")
            sql.execute(f"UPDATE users SET refcount = {new_ref_count} WHERE chatid = '{value[0]}'")
            sql.execute(f"UPDATE info SET earned = earned+2")
            db.commit()
        bot.send_message(message.chat.id, f"➖ Вы успешно <b>зарегистрировались</b>\n\n➕ В данном <b>боте</b> вы сможете <b>заработать</b> на <b>привлечении рефералов</b>.", parse_mode='html', reply_markup=mm)
        db.commit()

Answer 1

Problems due to the use of global, since these are global variables, they can be said to control everything. Because of this, if someone else enters cmd, the global variables are changed for the new member, and the past is "thrown into the abyss of despair"