Почему значение объекта меняется только внутри условия?

     
func(board, cards_obj) {
    const cards_player = [];
    const suit_player = [];
 
    let cards_player_split = [];
    let suit_player_split = [];
 
    console.log('Значение снаружи условия: ', board.amount_player_split);
 
    if ( board.player_split && board.amount_player_split < 21 ) {
        this.generate_cards(board.player_split, 1);
 
        board.player_split.forEach(obj => {
            cards_player_split.push(obj.card);
            suit_player_split.push(obj.suit);
        });
 
        board.amount_player_split = this.add_card(board, cards_player_split, suit_player_split, this.clone_html, cards_obj);
 
        console.log('Значение внутри условия: ', board.amount_player_split);
 
        this.amount_check_player(board);
    }
}