Starting with the release of Strategy ONE (March 2024), dossiers are also known as dashboards.
When running dossier in presentation mode or in Strategy Library, by default users can see visualization border when hovering over it as visible on screenshot below (shadow-like effect on the outside of the box).

This is default behavior of Strategy and is working as planned, however some users may want to remove this effect.
This can be easily fixed on dossier level in Format -> Dossier Formatting…

Upon opening, at the bottom of the window option “Disable highlight on hover when in presentation mode” needs to be ticked.

After doing so, highlight should be no longer visible.