Reduplication softens nouns into a cute / affectionate register, like English 'doggie' vs 'dog'. Common with pets and child language: 猫猫 'kitty', 兔兔 'bunny', 鱼鱼 'little fish'. Used freely by adults online.
culture
狗狗 also became internet shorthand referencing 狗狗币 (Dogecoin) in crypto contexts after 2021.
