Not if it's plainer/simpler. It already competes with them because it has nearly as much contrast as the foreground. Here's a very lazy edit that replaces the dark purple with the mid-purple. I think the image is much more readable like this simply because there's less contrast in the background now. Previously lost details like the edge of the cake and the balloon strings have become visible.

Thanks. But if I make it brighter, it would surely steal attention from foreground objects.

The dark purple in the background blends with the dark/midtone colours on the foreground objects, distorting their apparent shapes and making things harder to see. Consider placing it where it doesn't touch your dark areas, or excluding it entirely.