One issue I see with the RH sidebar is the node reveal no longer works correctly.
With the RH panel open the debug node is not scrolled into view (it is already in view - just behind the panel)

With the panel closed, the scroll into view works.

At a guess, this new viewport (the area inside the scroll bars) is not used in the reveal calculation.
Related question. Folk (me included) have commented on how difficult it is to sometimes see the flashing orange border (esp colour blind) and I am curious if this is something on the table for the modernisation?
Ref: Better accessibility on search result highlighting - #31 by knolleary