I was watching death note for the hundredth time, and realised that mogi doesn't eat the strawberry straight away but puts it in his pocket. He must've eaten it at some point. :
Kanzo Mogi | Death Note Wiki | Fandom
Kanzo Mogi - Death Note Wiki - Neoseeker
Death Note Wiki - October 25, 2004 [2007 in anime]: • Nori, an acquaintance of Misa's, switches outfits with Misa so that Misa can go on her date while Nori poses as