When using the desktop app on MacOS, there is a quirk when switching between item types. In my screenshots below, you will see that when I select a secure note to view, and then switch to login, I would expect the right column with the note item to be empty but it’s not. I would expect the behavior to clear that side of the window until I select a login item.
This is not likely a “bug” in that the the vault is apparently working as designed. The right hand pane continues to display the last chosen vault entry until a new vault entry is selected.
There is, however, a feature request to change this behavior. One you have graduated from “new user” to “basic user”, you will be granted 20 votes. IT takes about 30 minutes of browsing around the community, and you will receive a notice (in the top-right corner) when it happens. Perhaps add your vote to this topic.
While technically it may not be a bug, it’s odd behavior. I would expect that to disappear when changing item types. To me, it’s confusing to see it there, especially when trying to edit a different item.