I noticed this as I was refreshing pages left open from yesterday. The top bar is a few pixels deeper than it was, and there's a one pixel wide almost white stripe beneath it.
Hard to see the white stripe on this, which was my only site I hadn't refreshed that uses a non-white header, before & after…
& the same crop on Meta where the stripe is easier to see
Partly-scrolled image from Sound Design to confirm the stripe is actually part of the top bar…
Images from Safari but I checked Chrome is the same.
The bar depth difference itself is barely noticeable, the white stripe is irritating.
Bug or intentional?