Meta_query with key as an array

Question

I facing a problem with a meta_query where the meta_key's value can have multiple dates :

My meta field event_dates can have several dates like : 20220902,20220928

CODE EXPECTED :

$today = date( "Ymd");

$args = array(
    'post_type' => 'events',
    'meta_query' => array(
        array(
            'key'       => 'event_dates',
            'value'     => $today,
            'compare'   => '>='
        )
    )
);

With the help of other wpse's questions like here, I've try things like :

  ...
  'value'     =>  serialize( intval( $today ) ),
  ...

  // AND/OR
  // in the ACF admin field ("event_dates")
  a:1:{i:0;i:20220902;i:1;i:20220928;}

  // OR 
  20220902,20220928

I also try like a post I can't find again said :

foreach($event_dates as $dates) :

    add_post_meta( $inserted_id, 'event_dates', $dates );

endforeach;

My goal is to find posts where in this meta field (at least) one of those dates is older than today.

Some help please !! :)