A trick I use to identify the source of unknown search results is to compare the SERP to a search engine that I know uses the primary source (usually Bing or Go

A trick I use to identify the source of unknown search results is to compare the SERP to a search engine that I know uses the primary source (usually Bing or Google) indirectly. So for example, instead of comparing unknown results directly to the Bing SERP, I will compare it to Ecosia's SERP because it is powered by Bing will generally be less manipulated (i.e. closer to what Bing just returns in their API). Bing also adds a lot of other information to their own SERP which they might not make available in their API. It's definitely not a fingerprint, but the source of organic SERPs are almost always identifiable.