How can I put two variables in post__not_in like this:
'post__not_in' => $excludeHome, $excludePostSlide
When I do this only posts from first variable don’t show up from the others show up.
I can do that with array push like below but is there any different way to do it?
  @php
    wp_reset_postdata();
    global $excludeHome;
    global $excludePostSlide;
    array_push($excludeHome, $excludePostSlide[0], $excludePostSlide[1], $excludePostSlide[2], $excludePostSlide[3], $excludePostSlide[4], $excludePostSlide[5]);
    $args = [
        'post_type' => 'post',
        'orderby' => 'date',
        'category_name' => 'auto',
        'posts_per_page' => 6,
        'no_found_rows' => true,
        'post__not_in' => $excludeHome,
    ];
    $querySlider = new WP_Query($args);
  @endphp
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Answer
According to the wp_queryDocs, post__not_in accepts an array of post ids.
- It’s not clear that your global 
$excludeHomeand$excludePostSlidevariables are actually arrays. So make sure that they are arrays. - In order to use 
array_pushfunction, it’s better to use aforeachloop on the$excludePostSlidearray, rather than trying to push them by their index number! 
global $excludeHome;
global $excludePostSlide;
$excludeHome = is_array($excludeHome)
    ? $excludeHome
    : (array)$excludeHome;
$excludePostSlide = is_array($excludePostSlide)
    ? $excludePostSlide
    : (array)$excludePostSlide;
foreach ($excludePostSlide as $excludeSlide) {
    array_push($excludeHome, $excludeSlide);
}
$args = [
    'post_type'      => 'post',
    'orderby'        => 'date',
    'category_name'  => 'auto',
    'posts_per_page' => 6,
    'no_found_rows'  => true,
    'post__not_in'   => $excludeHome,
];
$querySlider = new WP_Query($args);