GNU is really its own thing and not reallyPOSIX anymore. So GNU is right even if they are wrong.
This is not me advocating for GNU. I use BSD utils myself.
On this issue, your were right in a way. My understanding is that the uutils version of dd was respecting the fullblock parameter, causing problems on slow pipes. GNU ignore this and was doing partial writes. Uutils has been modified to match GNU and is “working” now. At least, a tested patch has been submitted.
And……fixed.
A few days ago we had a “performance” bug. Before the stories had even been written, the uutils was made 50% faster than GNU.
Now we have an actual difference in behaviour. But it is again fixed before the stories could even go out.
The anti-Rust crew is really trying to celebrate hear but it seems like uutils is proving them wrong so far.
We will see what happens in production I suppose.