mySQL not save the correct data

I’m trying to create a task app. when saving it, the server says successful

[{"taskName":"Join Group","completed":true},{"taskName":"Follow Channel","completed":true},{"taskName":"Follow Twitter","completed":false},{"taskName":"Visit Website","completed":false},{"taskName":"Visit Launchpad","completed":false}]

However, it is not saved in the database, see the follow channel task

[{"taskName": "Join Group", "completed": true}, {"taskName": "Follow Channel", "completed": false}, {"taskName": "Follow Twitter", "completed": false}, {"taskName": "Visit Website", "completed": false}, {"taskName": "Visit Launchpad", "completed": false}]

Here the UI

const handleTaskClick = (e: React.MouseEvent<HTMLAnchorElement>, taskName: string, link: string, isTaskCompleted: boolean) => {
    e.preventDefault();

    if (!isTaskCompleted && username) {
      sessionStorage.setItem('currentPage', JSON.stringify({ taskName }));

      axios.post('/api/completeTask', { username, taskName })
        .then(response => {
          console.log('Updated Task Data:', response.data);
          setTaskData(response.data);
          window.open(link, '_blank');
        })
        .catch(error => {
          console.error('Error completing task', error.response?.data || error.message);
        });
    }
  };

and here the backend

// models/Task.js

const { sequelize, DataTypes } = require("../config/mysql-sequelize");

module.exports = (sequelize, DataTypes) => {
  const Task = sequelize.define('Task', {
    username: { type: DataTypes.STRING, allowNull: false },
    tasks: {
      type: DataTypes.JSON,
      defaultValue: []
    },
    claimedAmount: { type: DataTypes.FLOAT, defaultValue: 0 }
  }, {
    timestamps: true
  });

  return Task;
};

//  routes/task.js

const express = require('express');
const router = express.Router();
const fs = require('fs');
const path = require('path');
const { Task } = require('../models');

const getTasksConfig = () => {
  const filePath = path.join(__dirname, '../config/tasks.json');
  if (fs.existsSync(filePath)) {
    const fileContent = fs.readFileSync(filePath, 'utf8');
    try {
      return JSON.parse(fileContent);
    } catch (error) {
      console.error('Error parsing JSON:', error);
      return [];
    }
  } else {
    console.error('File not found:', filePath);
    return [];
  }
};


router.get('/tasksConfig', (req, res) => {
  try {
    const tasksConfig = getTasksConfig();
    res.json(tasksConfig);
  } catch (error) {
    res.status(500).json({ message: 'Error loading tasks configuration' });
  }
});

// Endpoint untuk mendapatkan data tugas pengguna
router.get('/taskData', async (req, res) => {
  const { username } = req.query;
  try {
    const taskData = await Task.findOne({ where: { username } });
    if (taskData) {
      res.json(taskData);
    } else {
      res.status(404).json({ message: 'Task data not found' });
    }
  } catch (error) {
    res.status(500).json({ message: 'Server error' });
  }
});

router.post('/completeTask', async (req, res) => {
  const { username, taskName } = req.body;

  console.log(`Received request to complete task: ${taskName} for user: ${username}`);

  try {
    const tasksConfig = getTasksConfig();
    const taskConfig = tasksConfig.find(t => t.taskName === taskName);

    if (!taskConfig) {
      console.log(`Task configuration not found for taskName: ${taskName}`);
      return res.status(400).json({ message: 'Invalid task name' });
    }

    let taskData = await Task.findOne({ where: { username } });

    if (!taskData) {
      console.log(`No task data found for username: ${username}. Creating new task data.`);
      taskData = new Task({
        username,
        tasks: tasksConfig.map(t => ({ taskName: t.taskName, completed: false })),
        claimedAmount: 0,
      });
    } else {
      console.log(`Existing task data found for username: ${username}`);
      const existingTaskNames = taskData.tasks.map(t => t.taskName);
      const newTasks = tasksConfig.filter(t => !existingTaskNames.includes(t.taskName));
      if (newTasks.length > 0) {
        console.log(`Adding new tasks: ${JSON.stringify(newTasks)}`);
        taskData.tasks.push(...newTasks.map(t => ({ taskName: t.taskName, completed: false })));
      }
    }

    const task = taskData.tasks.find(t => t.taskName === taskName);

    if (task) {
      if (!task.completed) {
        console.log(`Completing task: ${taskName} for user: ${username}`);
        task.completed = true;
        taskData.claimedAmount += taskConfig.reward;

        await taskData.save();
        console.log(`Task completed. Updated task data: ${JSON.stringify(taskData)}`);
        res.json(taskData);
      } else {
        console.log(`Task: ${taskName} already completed for user: ${username}`);
        res.status(400).json({ message: 'Task already completed' });
      }
    } else {
      console.log(`Task: ${taskName} not found in task data for user: ${username}`);
      res.status(400).json({ message: 'Task not found' });
    }
  } catch (error) {
    console.error('Error completing task:', error);
    res.status(500).json({ message: 'Server error' });
  }
});



router.get('/getTaskAmount', async (req, res) => {
  const { username } = req.query;

  try {
    const taskData = await Task.findOne({ where: { username } });

    if (taskData) {
      res.json({ claimedAmount: taskData.claimedAmount });
    } else {
      res.status(404).json({ message: 'User not found' });
    }
  } catch (error) {
    res.status(500).json({ message: 'Server error' });
  }
});

module.exports = router;

What causes data not to be saved correctly to the database?