One of the missing features in the QoS System is a classifier for number bytes transferred. Right now there’s Port rules and IP based rules to put a connection in a particular class, but no sorting by number of bytes transferred.
For example, someone may want to de-prioritize large file downloads into a lower class of traffic. (although fq_codel makes such manual classifying generally less necessary , it would still be nice to have) Linux has the power to do this with conntrack afaik
Another interesting classifier would be ipset. The is way, the community could maintain a set of ip addresses associated with windows updates or steam downloads which could also be de-prioritized (these types of update services are notorious for using technology like FASTTCP and multithreading to defeat fq_codel, and need to be manually punished)