Is this considered as kufr or may be exempted

Assalamu alaikum last day in Google I found that a famous person is not a member of ahlu sunnah , so I was shocked told about this to my mother and my aunt , now I am scared is not a member of ahlu sunnah is synonymous as calling him kafir if yes , is this an act of kufr. I don't intend to commit kufr or I don't intend to call he / she as kafir , and also I don't know the meaning of ahlu sunnah it was surely unintentional , at that time I thought ahlu sunnah was some course for becoming scholars or something Is it considered as kufr please mention it is kufr or not Please answer as soon as possible please