There is no css name input field at Drupal 8.9.2 after installed the module so that it is totally unusable.
However I notice that there is an additional class "hello-here2" added to every menu's li element.
<li class="menu-item hello-here2">
Closed: works as designed
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It's likely this issue predates Contrib.social: some issue and comment data are missing.
I don't think that this is the modules intention, this module doesn't provide any free text form/field etc to add class names, its not what the module suggests it does.
It grabs the menu title and adds it as a class, which is what you're seeing.