performance impact of bigint vs varchar in mysql query

Mysql giving bad performance while passing column value as bigint and column created with data type is varchar. Below is my create table query and index created on 3 columns(user_id,category,status). I am using spring jpa to interact with mysql and also using native query to get data from mysql.

CREATE TABLE order (
    id          int NOT NULL AUTO_INCREMENT,
    user_id     varchar(50) NOT NULL,
    category    varchar(255) NOT NULL,
    amount      decimal(13,2) NOT NULL,
    status      varchar(50) NOT NULL,
    created_at  timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
    PRIMARY KEY (id),
    KEY idx_order_user_category_status (user_id,category,status),
    KEY idx_order_created_at (created_at)
);

@Query(
    value =
        "SELECT month(created_at) mm, year(created_at) yy, sum(amount) tpv "
            + "FROM order "
            + "WHERE user_id = :userId "
            + "AND category = 'BILL' "
            + "AND status IN ('SUCCESS','PENDING') "
            + "AND created_at >= :startDate AND created_at < :endDate "
            + "GROUP BY mm, yy",
    nativeQuery = true)
List<List<Object>> getTpvByUserIdAndDateBetween(
    @Param("userId") Long userId,
    @Param("startDate") LocalDate startDate,
    @Param("endDate") LocalDate endDate);

SELECT month(created_at) mm, year(created_at) yy, sum(amount) tpv FROM order WHERE user_id = ? AND category = 'BILL' AND status IN ('SUCCESS', 'PENDING') AND created_at >= ? AND created_at < ? GROUP BY mm, yy
TRACE o.h.type.descriptor.sql.BasicBinder.bind(64) - binding parameter [1] as [BIGINT] - [24463608]
TRACE o.h.type.descriptor.sql.BasicBinder.bind(64) - binding parameter [2] as [DATE] - [2022-07-31]
TRACE o.h.type.descriptor.sql.BasicBinder.bind(64) - binding parameter [3] as [DATE] - [2022-10-01]
INFO  c.b.b.p.services.impl.OrderService.getCcBpMonthlyTpv(672) - db query response time:2398


@Query(
    value =
        "SELECT month(created_at) mm, year(created_at) yy, sum(amount) tpv "
            + "FROM order "
            + "WHERE user_id = :userId "
            + "AND category = 'BILL' "
            + "AND status IN ('SUCCESS', 'PENDING') "
            + "AND created_at >= :startDate AND created_at < :endDate "
            + "GROUP BY mm, yy",
    nativeQuery = true)
List<List<Object>> getCcBpTpvByIdAndDateBetween(
    @Param("userId") String userId,
    @Param("startDate") LocalDate startDate,
    @Param("endDate") LocalDate endDate);

SELECT month(created_at) mm, year(created_at) yy, sum(amount) tpv FROM order WHERE user_id = ? AND category = 'BILL' AND status IN ('SUCCESS', 'PENDING') AND created_at >= ? AND created_at < ? GROUP BY mm, yy
TRACE o.h.type.descriptor.sql.BasicBinder.bind(64) - binding parameter [1] as [VARCHAR] - [24463608]
TRACE o.h.type.descriptor.sql.BasicBinder.bind(64) - binding parameter [2] as [DATE] - [2022-07-31]
TRACE o.h.type.descriptor.sql.BasicBinder.bind(64) - binding parameter [3] as [DATE] - [2022-10-01]
INFO  c.b.b.p.services.impl.OrderService.getCcBpMonthlyTpv(686) - db query response time:8

Below are the cases after my analysis:

• passed user_id as long and long was interpreted by jpa as bigint and got response in 2398ms.
• passed user_id as string which was interpreted by jpa as varchar and got response in 8ms.

Tech stack:

• JDK: 11
• Spring boot version: 2.5.5
• mysql version: 8.0.23

Note:

Approx 3 Million records present in table

Questions

1. How does mysql behave if column value is passed as different data type while doing a select?
2. Both gave correct result but one gave worst performance and other scenario gave best performance. Why?