The one thing that I can see wrong is that this
$_POST['acf']['submitted'] has no value. ACF fields are submitted using the field key and not the field name, for example
$_POST['acf']['field_abc123']. So you’ll need to substitute your field key there to get any type of a result. More than likely your currently generating an undefined index error in php. There is more information on this here https://www.advancedcustomfields.com/resources/acf-save_post/ where it talks about using this other filter before ACF has saved values.
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