I created 2 hybrid torrents, A and B, both contains same files and has same trackers, uploaded A to public, It's been downloaded hundreds of times and there's no shortage of clients in the peer list that support v2.
use Tixati 3.19 and BiglyBT (supports v2) download B, it stuck at 0%, didn't get anything from A. Some people say that need trackers support this feature, is that true? Did you ever test succeed?
like this: https://www.reddit.com/r/qBittorrent/comments/t6pj7q/bittorrent_v2_not_working_as_expected/
Cross swarms by v2 feature is not implemented yet in any client I know, yes, the latest versions of BiglyBT support Swarm Merging by v2 hash, but Swarm Discoveries is other thing.
As far as I know biglybt Swarm Discoveries work by matching size of files, but even in this case it takes a lot of time (millions of torrents) to crawl DHT network.
To implement something like this clients would announce file hash list DHT, which would come up as a big load on network itself. Better option would be giving this load to trackers, but there's no standard for this yet, announcing something like: info_hash -> [file_hash1, file_hash2...]
would need another connection method, could be a http POST request.
Biggest question here is the trackers willing to take this load.
P.S.
Did you name your torrent "testing cross swarms"? :D
lol nope, I named it as a string of random letters.
After downloading for a while, although B didn't get anything from A, but some IPs from GE, FR, US, VN, and so on appeared in the peer list, and their client names are rather strange and usually not seen, e.g. the VN ip's client name is "VN 3.xxx", do you know what they are?