It is very easy to recover a previous version of the description field in Jira. Jira keeps a full change log / audit log of every change to the description field and other fields. You can definitely roll back to an old version of the description field or see what changes were made and when by whom.
This is one of those cases when Jira is suffering from its UI/IA mess. It has lots of good feature but the discoverability is horrendous, which leads to so much user (my) confusion.
https://www.tutorialspoint.com/jira/jira_view_change_history...