Hi and welcome to the forum!
First off, can you tell us a little about your setup (I see it’s Windows 10 from your screenshot, but what build? 1903, 1909 2004 etc.) and what graphics device you are using (Nvidia, Intel integrated, AMD etc.)?
As with all such things, what was the last change you remember making on your computer (Windows updates etc.)?
If you go to preferences, (Edit menu, Preferences) and click the display tab, at the bottom right you will see “Rendering API”, does that say DirectX or OpenGL? Try changing that an restarting SpectraLayers to see if that makes any difference.