I've written more about this problem here .
I wonder how TCP BBR would react here. If I understand it right, it wouldn't need RED to back off: the increased latency of buffers filling up would do that automatically. But BBR also wouldn't let the occasional dropped packet make it back off.
TCP BBR would still rely on RED/WRED to compute the connection rate estimate initially, then it would attempt to send below that rate to avoid packet loss. If packet loss is detected it would recompute the estimated connection rate.
I found this page  useful, especially the graphs.