Why Sequelize create new connection for every query?

I have a code that analyze a lot of data received by websocket and from some time found that MySQL DB (JawsDB on Heroku) return error message:'User 'xxxxx' has exceeded the 'max_user_connections' resource (current value: 10)'.

I understand that it is MySQL limit, what I am do not understand - why is my code creates NEW connection on each query (while pool options defined).

How I figured it out: placed breakpoint on ${proj}/node_modules/sequelize/lib/dialects/mysql/connection-manager.js:

class ConnectionManager extends AbstractConnectionManager {
  ....
  async connect(config) {
    // HERE IS PUT BREAKPOINT WHICH HIT FOR EACH QUERY
    const connectionConfig = {
        ....
    };

    try {
      const connection = await new Promise((resolve, reject) => {
        const connection = this.lib.createConnection(connectionConfig);
        ....
    } catch (err) {
      switch (err.code) {
        default:
          // '{"code":"ER_USER_LIMIT_REACHED","errno":1226,"sqlState":"42000","sqlMessage":"User 'xxx' has exceeded the 'max_user_connections' resource (current value: 10)"}'
          throw new SequelizeErrors.ConnectionError(err);
      }
    }
  }
}

Here is how Sequelize instance created (once, I checked it):

const sequelize = new Sequelize(config.databaseUri, {
    dialect: 'mysql',

    dialectOptions: { decimalNumbers: true },

    pool: {
      max: 5,
      min: 1,
      idle: 10000
    }
});