Cardinal Parolin was in Angola on Saturday, where he was ordained Archbishop-elect.

Source: https://www.eyeradio.org/vatican-secretary-of-state-parolin-arrives-in-juba/

He was suffering from a lung infection and was too unwell to deliver the speech, so it was given by Cardinal Pietro Parolin, the Vatican's Secretary of State.

Source: https://www.dailymail.co.uk/news/article-12818997/Pope-Francis-calls-elimination-fossil-fuels-historic-speech-climate-conference-Cop28.html?ns_mchannel=rss&ns_campaign=1490&ito=1490

Speaking to reporters on the sidelines of a conference in Rome, Parolin said the Vatican was working on a meeting between the pope and relatives of the hostages but gave no time frame.

Source: https://newsinfo.inquirer.net/1861785/pope-to-meet-relatives-of-hostages-palestinians-with-family-in-gaza