htm speciall characters in configuration fields

Site Url: Innerlightcrystals.co.uk/sales
PHP version: 7.3

There is an issue with including any htmlspecial characters in fields in Admin configuration.
For example:
The default Bread Crumbs Navigation Separator in configuration>layout settings is  ::  if you edit and save without changing the value it becomes  ::  do it again and you get  :: and so on.

I have gone in to phpmyadmin and edited the value back to the correct value which works. This however would be an issue for any field that contains &, ",>,<, and may be more.

Think part of the issue is that double encoding is turned on for html special characters. so existing special chars like & are being converted again. Even with that set to false on line 207 ```php
eval('$value_field = ' . $cInfo->set_function . '"' . htmlspecialchars($cInfo->configuration_value, ENT_COMPAT, CHARSET, FALSE) . '");');

in configuration.php. This stops the duplication of the & characters but still dose not allow you to enter html as the characters are still converted.

Have found a possible solution:
changing line 24 :```php
$configuration_value = zen_db_prepare_input(htmlspecialchars_decode($_POST['configuration_value']));

to include htmlspecialchars_decode appears to work.
Ignore previous post.
Not sure what the implications of doing this are so if this proposal is ok please let me know.

The issue is caused by strict sanitization performed on configuration_key entry in the admin's sanitization in absence of specific sanitization by key. A path for addressing this is in ZC 1.5.7 and discussed elsewhere in this forum.