WordPress post meta array

I'm adding post meta for custom post type. The meta value is an array

Array (
    'value',
    'value',
    'value'
)

Using add_post_meta() works fine, but when I retrieve post meta, it returns a multi-dimentional array

Array (
    [0] => Array (
        [0] => value,
        [1] => value,
        [2] => value
    )
)

Why is a multidimentional array returned when I'm using the following

$myarray = get_post_meta( $postid, 'meta_key', false );

Syntax for get_post_meta as state below reference link is

https://developer.wordpress.org/reference/functions/get_post_meta/

get_post_meta ( int $post_id, string $key = '', bool $single = false )

Retrieve post meta field for a post.

Return: (mixed) Will be an array if $single is false. Will be value of meta data field if $single is true.

Try something like below

get_post_meta( $postid, 'meta_key', true );