note when saving json with unicode by json_encode()

save-json.php

$content = [];
// ...
$my_post = array(
    'post_title' => 'aaa',
    'post_content' => str_replace("\\", '\\\\', json_encode($content)), // avoid saving \u1ec5 to u1ec5
    'post_status' => 'pending',
    'post_author' => 0,
);

// Insert the post into the database
$id = wp_insert_post($my_post);