Summary:
When you delete a group that has been used to limit the visibility of comments, you're given the option to choose another group to make those comments visible to.

When you delete a role that has been used to limit the visibility of comments, no prompt is given. The role is removed and the comments are still flagged as being visible to users associated with the missing role. These comments are effectively orphaned.

Steps to Reproduce:

1. Create an issue comment and restrict it to a specific role
2. Delete the role
   Result: Comment is invisible, orphaned in the database.
   Expected: either

• when deleting the role an option to move comments to another role is done or to make them public.
• comments are made accessible to administrators role

Workaround:
Perform a database update as mentioned on How to recover the comments viewable by a Project Role which has been deleted