Choose Media ID as Value Format in metabox setting. Add this nto custom query in Bricks Builder

$gallery = get_post_meta( get_the_ID(), 'gallery', true);
// Chaage gallaery to tour filed name

if(!empty($gallery)) {
  
$images = explode(",", $gallery);
$galleryArray = array_map('intval', $images);

return [
    'post_type'      => 'attachment',
    'post_mime_type' => 'image',
    'post_status'    => 'inherit',
    'orderby'        => 'post__in',
    'post__in'       => $galleryArray,
    'posts_per_page' => -1,
]; }

else {
  	return [];
}

In image element inside query, set post_id as the image source.

Source:
Bricks Builder Forum

Query Image Gallery Sub Field inside Jet Engine Repeater

If you have jet engine emta field repeater and sub field type Gallery. You can display it on bricks builder. First set the repeater field using dynamic data of repeater field name in dynamic data. Then inside the query, create custom query with code below:

Note: Repeater field name is gallery and sub field name is gallery_repeater.