In 2015, after he injured his left knee ligament, doctors found a malignant tumor on his left leg. Later on, he won the battle against cancer.[4]
Upon winning the medals in 2021, Fonseca questioned in his ironic speech to Adidas and Puma: "This medal I will dedicate to Adidas and Puma because they said I had no capacity to be a Puma representative. I dedicate this medal to Puma and Adidas leaders. I've already shown that I'm two-time world champion, third at the Olympic Games. Which status do I need to be sponsored by Adidas and Puma?"[5]
In 2022, he was a candidate for PSP, the national civil police force of Portugal, but failed the entrance examinations at the Escola Prática de Polícia (police school).[6][7]