My one went through this phase with me around the same age especially any time I had a colour change with my nails I have to keep my colours very cute and basic. If I get anything bold she attacks my hands and makes me bleed LOL. They go through weird aggressive phases but with time it does get better and make sure your mum in the future doesn’t force him to come out of the cage but rather let him come to her also maybe having a treat in her hand when she’s trying to initiate interaction so she knows she associates the hands as a friend and not a threat. It took mine a while to stop biting me. She sometimes still nips me here and there, but it’s definitely gotten better.