What common mistake do developers make with Facade scope, why does the mistake cause problems, and what is the safer approach?

What common mistake do developers make with Facade scope, why does the mistake cause problems, and what is the safer approach? One recurring problem with facade scope is applying it without understanding the boundary it protects. Assuming a facade call automatically makes a method pure or side-effect free; the underlying service still performs real work. In addition, A facade is most useful when it keeps an operation expressive without hiding important business dependencies. Safer engineering approach: keep the responsibility in the correct layer, use the framework's supported API, validate and authorize inputs, avoid hidden side effects, and verify the behavior with tests.