mpp-global-shared-gallery-allow-edit-delete-media.php

<?php
/**
 * Check if gallery is shared or not
 *
 * @param int $gallery_id Gallery id.
 *
 * @return bool
 */
function buddydev_is_shared_gallery( $gallery_id ) {
	$is_shared = mpp_get_gallery_meta( $gallery_id, '_mpp_is_all_upload_allowed', true );

	return $is_shared ? true : false;
}

add_filter( 'mpp_user_can_edit_media', function ( $allow, $media, $gallery ) {

	if ( ! is_user_logged_in() || ! buddydev_is_shared_gallery( $gallery->id ) ) {
		return $allow;
	}

	if ( ! $allow && get_current_user_id() == $media->user_id ) {
		$allow = true;
	}

	return $allow;
}, 10, 3 );

add_filter( 'mpp_user_can_delete_media', function ( $allow, $media, $gallery ) {

	if ( ! is_user_logged_in() || ! buddydev_is_shared_gallery( $gallery->id ) ) {
		return $allow;
	}

	if ( ! $allow && get_current_user_id() == $media->user_id ) {
		$allow = true;
	}

	return $allow;
}, 10, 3 );