Is describing a modern conversation between two people as "not permissible in Sharia" considered qadhf (slanderous accusation), and does it necessitate the punishment of eighty lashes, even if there was no accusation of zina (fornication/adultery)?

Informing someone that another person is speaking illicitly with a woman is not slander (qadhf) that necessitates the legal punishment (hadd). Slander (qadhf) is explicitly or implicitly accusing someone of adultery (zina). If someone becomes aware of an unlawful conversation between a man and a woman, they must denounce it according to their ability. However, they are not permitted to inform anyone else about it, except for a legitimate interest, such as seeking a fatwa (definition) or seeking assistance in changing the reprehensible act.