BBR's first ten round trips
A short download is almost entirely BBR's opening. The probe for bandwidth has not finished, the min-RTT filter still holds the first sample, and a 200 ms path has only given the control loop a handful of round trips before the file ends.
I stopped quoting a 4 MB pull as line rate. It is a statement about slow start and the first bandwidth probe. For a number that describes the path, I let the flow live past a few seconds, or I send several streams and throw away the first second of each. The kernel BBR in the Debian I run is v1. I am not switching kernels to chase a blog post about v3.