Version: I am using Plex version 8.17 (5542) on the Apple TV 4K recently updated to tvOS version 16.4 (20L497).
Details: The Classic view which can be adjusted in Settings no longer works after this latest tvOS update. The Content Layout setting allows for the adjustment to either Classic or Modern view, but no matter which one I select, it shows the Modern UI. This creates an accessibility issue, because the buttons on the details menu are too small for me to see. This started right after the Apple TV was updated to 16.4
I believe the modern layout is mostly about Plex displaying the background and details of the selected item on the Home Screen and Recommended tabs of the libraries.
The tvOS app still seems to enable/disable that when switching between classic/modern layouts for me.