Are jokes that describe a group of people as ignorant or foolish considered backbiting, especially if the speaker intentionally refers to a specific segment of Muslims?

There is no objection to jokes if they are free from backbiting and lying. Imam al-Nawawi inferred the permissibility of backbiting an unspecified person from the hadith of Umm Zar, where he mentioned that the women spoke about their husbands in a way they disliked, and this was not backbiting because their identities were unknown. The author of Majma al-Anhur also indicated that backbiting the people of a village is not backbiting because the intended party is an unknown few. Accordingly, the examples mentioned do not contain backbiting because the intended party is unknown and unspecified. However, the more pious approach is to avoid anything that offends and harms a Muslim, even if they are unknown.