I really appreciate you taking the time to help.
Posted this on Stackoverflow and got an answer (even though somebody else deleted the right answer before I could thank them).
For anybody else who comes across this, I need to convert it this way.
$image_id = get_post_meta( $row->post_id, $meta_key, true );
//$image_ids = unserialize($image_id);
$json = json_decode($image_id);
// load image src
// - https://www.advancedcustomfields.com/resources/field-types/image/
$src = wp_get_attachment_image_src( $json->cropped_image, 'cropped_image' );
It was a JSON object which needed to be decoded.
Thanks again for helping – means a lot to somebody who was completely stuck.