Bug: Content gets duplicated in editor on save with Bold & Label

We're currently using a custom label/tag in the editor but sometimes when we mix it together with Bold, the editor seems to break and duplicate the bold words. where we end up with a version of the bold words outside of the custom label but still in bold and a version of the word that's not bold but inside the label:
Before Save

After Save

Any idea why/how this is happening?

Hey there. This is a known bug. We are currently actively tracking it.
Can you send us the URL of your repository?
This will allow us to add you to the open ticket and give you updates when it's fixed.

This thread is being monitored as an open ticket in the internal Prismic issue tracker. The Prismic support team will update this post as we get more information from our dev team. If you have a similar use-case, you can ‘Flag’ this topic to reopen and add it here.