Multiplexed HTTP/3 BBR versus multi-connection HTTP/1

[Wesley Rosenblum]

When migrating from HTTP/1.1 to a protocol that supports multiplexing, such as HTTP/2 or HTTP/3, the number of connections an application uses is reduced, usually from around 6 connections to just 1. This would seem to have implications in terms of fairness, as presumably BBR is unaware that the single HTTP/3 connection is now carrying the data previously transmitted by 6 HTTP/1 connections, and would aim to "fairly" use only 1 connection's fraction of the total bandwidth. 

For example, say a network path was previously occupied by 12 HTTP/1 connections from 2 applications, each using HTTP/1 and evenly dividing the bandwidth between the two. One of the applications migrates to HTTP/3 and starts using a single HTTP/3 connection. Now this application would receive 1/7th of the total bandwidth, rather than the 1/2 it was receiving in aggregate before the migration.

I've seen that the Chromium CUBIC implementation has made accommodations for adjusting parameters to allow it to operate fairly against N-connections. Is there any recommendation for how a single connection running BBR can be adjusted to get its "fair" share of bandwidth against multiple HTTP/1 connections?

Thanks,

Wesley Rosenblum