No, there's no roll-back function for this.
You'll find the descriptions are preserved in the issue history, with "<content> was changed to empty during an edit (the bulk move)". But the only way to get them back would be to copy and paste each one.
I don't believe there is a possibility to rollback changes in Jira. However, if you are on Jira Server I would like to recommend you a plugin that could be helpful here: Time Machine (https://marketplace.atlassian.com/apps/1222498/time-machine?hosting=server&tab=overview)
Full disclaimer: I am the creator of the plugin.
With Time Machine you can revert changes to most of the issue fields that you are able to modify in Jira. It works by analyzing your issues' history and proposing old values to restore. I checked on my own instance and it looks like when moving projects, issue history is carried over from the original issue. As such you should be able to find the old description values for all your issues. Furthermore, it could serve as a safety net going forward.
Let me know if you found it useful.
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