Don't use bleach on your mousepad.

It will probably damage the surface coating, and the discoloration isn’t worth the risk.

Bleach is harsh. Most mousepads have a thin top layer (textured cloth or a slick coating) bonded to rubber. That coating isn’t designed to survive chlorine. Even diluted, bleach can eat through it, leaving the pad feeling rough, peeling, or yellowed. White pads are especially risky because bleach often causes a different kind of yellowing over time—ironic but true.

For tough stains, try a paste of baking soda and mild dish soap, or a dab of rubbing alcohol on a cloth. Scrub gently, rinse thoroughly, and let it dry flat. If that doesn’t work, the mousepad is cheap enough to replace.

That mousepad probably costs less than a replacement pair of jeans.