The labels are the ones from the form field. This looks like an error to me or is this intended?
1Password Version: Not Provided
Extension Version: 1.15.4
OS Version: Windows 10
Sync Type: Not Provided
Thanks for posting about this, @termac. The labels for the username and password fields in Login items should always read "username" and "password" instead of the label that was saved when creating the item. We're already fixing this internally and are aiming to get it out to everyone in the next beta release.