The attached image shows the same URL in the address bar in a normal (top) and private (bottom) window.
The contrast between the URL bar fill and the muted grey text of the non-host part of the URL is incredibly low and the URL path is basically impossible to read.

This is on a fresh installation of Orion (Version 1.1.3 (152), WebKit 625.1.8), running macOS 27.0.1. Toggling highlight colours either in System Preferences or in Orion's preferences doesn't change how this renders. Neither does toggling between the mini toolbar and the full-size toolbar.
The URL path text should be legible—rather than using what appears to be the same text colour used in non-private windows, it should use a shade of grey which contrasts sufficiently with the background.
Version 1.1.3 (152), WebKit 625.1.8