Your variables are not in functions scope.

My example of function:

function customPagination($paged = '', $max_page="") {
    global $wp_query;
    $big = 999999999;
    if( ! $paged )
        $paged = get_query_var('paged');

    if( ! $max_page )
    $max_page = $wp_query->max_num_pages;
    echo paginate_links( array(
        'total' => $max_page,
        'prev_next' => false,
        'prev_text'  => false,
        'next_text'  => false,
        'total' => $wp_query->max_num_pages,
        'mid_size' => 3
    ) );
}

and then calling it with your variables (just changed to camelCase)

customPagination($currentPage, $myQuery->max_num_pages); 

Hope it helps

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