@Wiz
To be honest I've not heard about many users those would really use multiple lists.

Me neither but I always look at things from different angles ie. product/feature differentiation, trailblaze if you will.

I don't mind it going but would like to see instead a better view of the saved favorites ie. pagination, sorting by listing expiry date, price and category maybe (to make up for the removal of the lists) and with of course the ability to notify if price / status changes occur which could be a small alert icon added next to the trash icon.

You can find message in oc-includes/osclass/controller/item.php
Plugin may not be able to stop it.

Checked, inactive listing is 404 for user that does not own listing or user that is not logged as admin.
You can test:
https://dev7.abprofitrade.eu/en/for-sale/dvd/cds-records/delta-8-thc-disposable-vape-variety-4-pack-bundle-i5632

I believe a better way of handling lists is to create and keep a default list option (created upon user account creation and cannot be deleted) with the option to set any list as default (Set as default) and when favoriting, provide options to choose lists to add favorited listings ie.

- When a user favorites a listing (regardless of whether logged in or out) and only the default list is present, it is added to the default list without automatically creating new lists.

- When a user favorites a listing, provide the user with option to select which list to add the favorites to if there is more than 1 (could be an overlay dropdown or search list box with current lists as values) and with option to create new list on the spot, and add a small check box to mark selected or new list as new default (this is very useful when user has a purpose in mind ie. renting apartments, buy car, looking for specific job etc.) - This also ensures the user's journey isn't interrupted (having to go back to the favorites page to create and manage lists).

- Change "CURRENT" to "DEFAULT"

- Change "Items in your list" to "{LIST_NAME} favorites list"

- Change the counter to only log or increment for logged-in users is simple

- Adding a counter to the favorite listings link is also simple

- Show list marked as default on list page load

- Option to move favorites between lists (reassign)

I added to form_passwrd.php, minlength="6" and required so that users are required to enter a password of at least 6 characters.
Here is the whole file:
<?php 
  $item_my = ModelBO::newInstance()->getItem($item_id); 
?>

<link href="<?php echo osc_base_url(); ?>oc-content/plugins/backoffice_manager/css/form.css" rel="stylesheet" type="text/css" />

<div class="row">
  <div id="bo_mgr_table">
    <label for="bo_mgr_passwrd"><?php _e('Enter Password', 'backoffice_manager'); ?></label>
    <input type="text" style="float:left;" name="bo_mgr_passwrd" id="bo_mgr_passwrd" value="<?php if($item_my['passwrd'] <> ''){echo $item_my['passwrd']; } else { echo Params::getParam('passwrd'); } ?>" size="20" minlength="6" maxlength="20" required />
    <div class="bo_info"><?php _e('Used to edit this listing', 'backoffice_manager');?></div>
  </div>
</div>

The following problem occurs: When I have the booking plugin activated, the message for correct password completion appears at the top, while when I disable booking, the message appears below the password box, which is probably the correct one.