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

What common mistake do developers make with Relationship inclusion, why does the mistake cause problems, and what is the safer approach? One recurring problem with relationship inclusion is applying it without understanding the boundary it protects. Returning the entire Eloquent model directly and unintentionally exposing internal fields that were never intended to be part of the API contract. In addition, Resources can include related data when those relationships are intentionally available. 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.