Based on the limited clues fans are given, there are a few options who could be beneath the Hedgehog mask. The first suggestion, from Reddit, says James Marsden (Westworld, Enchanted) is behind the mask. James is known for voicing a character in the Sonic the Hedgehog films, which would explain his costume. Another suggestion says the Hedgehog is James Corden, who is British (“sounds like Ringo”) and the carrot refers to his role in the film Peter Rabbit.
Source: https://www.distractify.com/p/who-is-hedgehog-the-masked-singer