I got confused when reading "Note that the 4 bytes at the start of the extension block are not encrypted, as required by [RFC8285]." - it seemed ambiguous to me. I'd suggest "Note that, as required by [RFC8285], the 4 bytes at the start of the extension block are not encrypted."
I got confused when reading "Note that the 4 bytes at the start of the extension block are not encrypted, as required by [RFC8285]." - it seemed ambiguous to me. I'd suggest "Note that, as required by [RFC8285], the 4 bytes at the start of the extension block are not encrypted."