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Cloudflare has an independent implementation of QUIC and HTTP/3, written in Rust. Somewhat confusingly, this is also called QUICHE and can be found on GitHub under cloudflare/quiche. Support BBR support has been announced as possible future work in a blog post about CUBIC and HyStart++ Support in quiche, but, as of November 2021, hasn't appeared in the official source tree yet.
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