please reply, someone from scratch team! please fix the problem!

As you'd expect, vector graphic costumes and backdrops look smoother, especially in fullscreen. But to take advantage of Scratch 2.0 vector graphics capabilities, the project's creator must draw or import vector graphic artwork into their project.

Since earlier versions of Scratch did not support vector graphics, most of the 3+ million projects on the Scratch beta website right now contain only bitmap graphics. But as people use Scratch 2.0 to create new projects, more of the projects you see will have vector graphics.