An error has occurred in the viewport display

There is a bug that when creating a new level, an infinite number of black spheres appear in the viewport.
It does not occur in other projects, it occurs only in the current project.

The black sphere is not displayed when playing.
It is displayed only when working.

Hey Tarrow100,

What you are seeing is the Visualization of the Volumetric Lightmap. You can disable this in your viewport by going to Show>Visualize and uncheck Volumetric Lightmap.