Seems like you should be correct. A shadcn button is just react, tailwind, and @radix/react-slot. But if you simply create a new shadcn Next.js template (i.e. pnpm dlx shadcn@latest init) and add a button, the "First Load JS" is ~100kB. Maybe you could blame that on Next.js bloat and we should also compare it to a Vite setup, but it's still surprising.