exterior wall putty

Please tell me about the problem of cracking putty on the decorative surface. The formula is : cement 400, quartz sand + heavy calcium carbonate gradation 600, Wacker redispersible polymer powder 3%, 20,000 viscosity cellulose ether 0.15%, water reducing agent 0.3%. 6mm glass fiber chopped...

The surface of the cement-based water-resistant putty is shiny and delaminates after grinding, forming a psoriasis-like appearance. How to improve it? How to avoid this problem from construction side? Here is the formula: 32.5 white cement 15%, redispersible polymer powder 0.5%, cellulose 0.4%...