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

What common mistake do developers make with Required rules, why does the mistake cause problems, and what is the safer approach? One recurring problem with required rules is applying it without understanding the boundary it protects. Validating a value but then updating the database with the complete unvalidated request payload. In addition, Required rules ensure a field is present before the application uses it. 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.