My Baby Brother Got My Old Toys and I'm So Mad

So my baby brother got all my old toys. He's three now, so he was getting into everything anyway, but when Mom gave him my action figures and my favorite plushie from childhood, it really hit me. It wasn't like she asked me first or anything; one day they just vanished. Now his room looks like a cross between a superhero museum and an animal kingdom diorama. I get that I'm the middle sibling, so usually I'm supposed to be okay with stuff like this. Mom says he's too young for things I've outgrown anyway, but it still feels wrong. My baby brother doesn't even know these toys were mine; to him, they're just cool things that suddenly appeared. I remember putting those action figures together piece by piece and spending hours creating epic battles with my plushies. It was my happy place. Now every time I see them in his room or on a shelf in the house, this weird mix of nostalgia and anger washes over me. Like why didn't Mom just ask? Did she think it would make me happy to know he's playing with things that were special to me? I've tried talking to her about it but every time I bring up the toys, she gets all defensive or says something like 'You're too old for those' which isn't helping at all. It's not just about the toys though; it feels like everything from my childhood is being taken and given to him without asking me. So, am I totally overreacting here? Or do other middle siblings feel this way sometimes too?