Ghost Pro.
Using Chrome or Firefox with dark mode selected in the admin panel, and creating a new post:
Add text and then save without a headline entered. The URL field is created as “untitled-1”.
Now enter a headline.
The URL field remains unchanged.
Close the article, and select light mode in the admin panel.
Reopen the article, and add a headline, and the URL field updates.
Regular users of the admin dark mode also report that the URL field cannot be changed on an existing article, published or not. That changes entered directly in the URL box will not save.
Same users report that it works as expected in light mode.