You probably don't want to do what is described in this document. Seriously consider just leaving things alone.
Because Qbittorrent, and most all torrent clients, still use HTTP/1.1, they typically do not reuse connections for multiple announces of different torrents to the same tracker announce URL. As the number of torrents goes up, there ends up being a lot of traffic back and forth just re-establishing a connection for each announce. This is highly inefficient, and while it is not really a problem for most users, or even most tracker operators, it is something that can start to be noticed at at the tracker level at a very large scale.
Using a more modern protocol, like HTTP/2, addresses this inefficiency by reusing an established connection. Unfortunately, Transmission is really the only torrent client that implements HTTP/2 right now. For Qbittorrent, the issue resides in an underlying library, libtorrent. The issue was raised in 2020,