MySQL 8.0 Triggers Current_User not working

I have this trigger that inserts a row to a table

CREATE 
    DEFINER=`root`@`localhost` 
    TRIGGER `user_log_AFTER_INSERT` 
    AFTER INSERT ON `user_log` 
FOR EACH ROW 
BEGIN
    INSERT INTO audit_trail 
    values( aud_no, 
           ( SELECT user_acc_id 
             from user_accounts 
             where user_username = REPLACE( CURRENT_USER, '@localhost', '')), 
           ( SELECT user_fname 
             from user 
             where user_id = ( SELECT user_acc_id 
                               from user_accounts 
                               where user_username = REPLACE( current_user(), '@localhost', ''))), 
           current_date(), 
           current_time(), 
           "logs in and out"); 
END

My problem here is that the CURRENT_USER is not working, when I tried to use another account it does not insert the right user account. What is it does is, it uses the account root@localhost instead of my CURRENT_USER.

So far I have tried changing the CREATE DEFINER=`root`@`localhost` instead of root I use a different account and it work. but What I want is to make it dynamic, It must insert the current_user who made changes to the database not root@localhost. Thanks

Since I cant get the right user inside the trigger using current_user() and user() but works fine on Stored Procedure. What I did is I create a Stored Procedure and call it inside the trigger.

Stored Procedure

CREATE DEFINER=`root`@`localhost` PROCEDURE `insert_log`()
BEGIN
    INSERT INTO audit_trail 
    values( aud_no, 
           ( SELECT user_acc_id 
             from user_accounts 
             where user_username = REPLACE( user(), '@localhost', '')), 
           ( SELECT user_fname 
             from user 
             where user_id = ( SELECT user_acc_id 
                               from user_accounts 
                               where user_username = REPLACE( user(), '@localhost', ''))), 
           current_date(), 
           current_time(), 
           "logs in and out"); 
END

Trigger

CREATE DEFINER=`root`@`localhost` TRIGGER `user_log_AFTER_INSERT` AFTER INSERT ON `user_log` FOR EACH ROW BEGIN
        CALL insert_log();
END