It certainly can be, but it's not guaranteed. Clean room design is one way to avoid a legally ambiguous situation. It's not a hard requirement to avoid infringe

It certainly can be, but it's not guaranteed. Clean room design is one way to avoid a legally ambiguous situation. It's not a hard requirement to avoid infringement. For example, the US Supreme Court ruled that Google's use of the Java APIs fell under fair use. My point is: just because certain source material was used in the making of another work does not guarantee that it's infringing on the rights of that original IP.