In all cases, the triangle has the wrong color. It should match the link inspector's header.
The triangle is constructed using 2 pseudo elements: a white triangle in the foreground and a gray triangle for the border. Since this is constructed from stacked elements, the foreground element needs to have 100% opacity. Currently the background color value for the header is wmui-color-accent90 at 50% opacity so setting the same value won't work.
When the first annotation is selected, there's a transparent gray overlay covering the triangle. This goes away upon clicking outside of the annotation. The same overlay shows up while pressing previous/next button (video attached).