Is backbiting an unknown person, such as the owners of pseudonyms in internet forums, considered among the forbidden backbiting in Sharia?

Among the conditions for backbiting to be unlawful (haram) is that the person being backbitten must be known. If they are unknown, neither their name nor their identity being recognized, then it is not considered unlawful backbiting, provided that this does not lead to searching for them or identifying them. As for participants in forums using pseudonyms, if they are known by sight to the listener, then mentioning them with what they dislike is unlawful backbiting. However, if they are unknown to the listener, then it is not among the unlawful forms of backbiting.