Because of Scratch's color contrast update, the background color went from blue to purple, and there's also an option which makes the blocks paler. I'm completely satisfied with this change, as long as everything else is still the same. But when a project is loading, as well as when you search for something, it's still the same shade of blue. Since all other instances of blue have been replaced with purple, it feels out of place when they don't. I believe they left them in as memories, but they probably just forgot.
Music: "Reaching Out" by Kevin MacLeod
