Is expiation (kaffara) obligatory for someone who committed adultery out of ignorance and then repented sincerely, and who prayed without ritual purity due to their ignorance of its ruling during a previous period of their life?

Adultery is one of the gravest sins and indecencies, and Allah the Almighty has forbidden it. Whoever commits it shall face punishment and have their torment multiplied on the Day of Resurrection, except for those who repent, believe, and do righteous deeds. Indeed, Allah will replace their evil deeds with good ones. Sincere repentance from adultery is obligatory. As for prayers performed without purity, they are not valid, and they must be made up.