`curl -i https://cdn.pika.dev/preact` https://cdn.pika.dev/preact` redirects me to a dist-es2019 package (I assume because it detects my user-agent supporting t

`curl -i https://cdn.pika.dev/preact` https://cdn.pika.dev/preact` redirects me to a dist-es2019 package (I assume because it detects my user-agent supporting that) but isn't showing anything like a `Vary: User-Agent` header. Won't this break for any situation in which users with different browsers share a proxy server? (also tried with Chrome, didn't see a Vary there either)