Why splice syscall fails when my program runs on Linux but succeeds when it runs in gdb?

I try to run a book's sample code. Its function is to accept a line of input and output it to the standard output and operation parameters specified file. Here is the code:

#include <assert.h>
#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <fcntl.h>

int main( int argc, char* argv[] )
{
    if ( argc != 2 )
    {
        printf( "usage: %s <file>\n", argv[0] );
        return 1;
    }
    int filefd = open( argv[1], O_CREAT | O_WRONLY | O_TRUNC, 0666 );
    assert( filefd > 0 );

    int pipefd_stdout[2];
        int ret = pipe( pipefd_stdout );
    assert( ret != -1 );

    int pipefd_file[2];
        ret = pipe( pipefd_file );
    assert( ret != -1 );

    //the first splice()
    ret = splice( STDIN_FILENO, NULL, pipefd_stdout[1], NULL, 32768, SPLICE_F_MORE | SPLICE_F_MOVE );
    assert( ret != -1 );

    ret = tee( pipefd_stdout[0], pipefd_file[1], 32768, SPLICE_F_NONBLOCK ); 
    assert( ret != -1 );

    //the second splice()       
    ret = splice( pipefd_file[0], NULL, filefd, NULL, 32768, SPLICE_F_MORE | SPLICE_F_MOVE );
    assert( ret != -1 );

    //the third splice()
    ret = splice( pipefd_stdout[0], NULL, STDOUT_FILENO, NULL, 32768, SPLICE_F_MORE | SPLICE_F_MOVE );
    printf("errno:%d\n",errno);
    assert( ret != -1 );


    close( filefd );
        close( pipefd_stdout[0] );
        close( pipefd_stdout[1] );
        close( pipefd_file[0] );
        close( pipefd_file[1] );
    return 0;
}

After i compiled the code, i ran it and typed "123", it can't output to stdout, the third splice() fails and errno is 22. here is the screenshot of result: p1

And when i use gdb to run the code, it works normally. Here is the screeshot: p2

kernel version: 4.19.163-1

gcc version: 10.2.0

gdb version: 10.1

my compile command: g++ test.cpp -g -o LinuxServer

my run command: ./LinuxServer test.txt

my gdb command: gdb LinuxServer

So why the splice syscall fails when my program runs on Linux but succeeds when it runs in gdb?