You need to pass the ID of the ‘p_image’ when calling the text field tied to it. So in your example:
This: the_field('custom_pinterest_description')
Should be updated to this: the_field('custom_pinterest_description', $image['ID'])
That tells ACF to get the ‘custom_pinterest_description’ field linked to the image with that ID.
Further examples and details can be found here: https://www.advancedcustomfields.com/resources/adding-fields-media-attachments
