The Jira labs feature in your first screenshot is specific to looking at Jira issues in a Software project via the board/backlog view. With that option enabled, the issues will appear as a popup in browser instead of appearing on the right side of the board view itself.
The second screenshot is actually using the new UI for Jira Cloud already, but this specific view is not expected to be affected at all by the Jira labs setting you have there. That specific view appears to be looking at the issue detail view when reached from the issue navigator, or going directly to the URL for that specific issue. That appears to be correct to me.
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