Scrubbing is the process of making an object with a smooth surface not smooth, so that light shines on the surface to form diffuse reflection. For example, frosted glass makes it opaque, and frosted leather makes it not as bright as ordinary leather.
The protective sleeve used by the mobile phone prevents the mobile phone from being damaged when it falls. Frosted means that the outer surface of the mobile phone case is covered with frosted feel and comfort, and it can also prevent fingerprints.