What is the cash-in-sofa scandal involving South African President Ramaphosa?

South African President Cyril Ramaphosa is facing calls to resign for covering up the theft of a large sum of foreign currency, which was hidden in a sofa, from his farm in 2020. He said thieves ‌had ⁠stolen $580,000 from the sofa at his Phala Phala game farm, though a former intelligence official said the amount stolen was $4 million.