I'm quoting from https://www.reddit.com/r/Piracy/comments/cpzix0/qbittorrent_anonymous_mode_useful_with_v_p_n/

AtlanticJack Wednesday, August 14, 2019 at 4:11:29 AM EDT who wrote about the topic:

That's not how I understand it. In older versions it does disable LPD DHT etc but in versions since v3.3.0 it disables the client's fingerprint, creates an empty string for the user agent and doesn't expose other identifying information directly yo the public such as IP, port etc.

The LPD DHT etc is now covered in the proxy section by "Disable connections not supported by proxies".

I use anonymous mode and also disable connections not supported by proxies, still seem to get plenty of seeds and peers via DHT and PeX though.

I know that copyright trolls have used modified versions of torrent clients to join swarms and log the participants IP. Well they wouldn't get my IP because I'm using a proxy or vpn but they also wouldn't get any fingerprints or user agent info from my qBittorrent client if I'm using Anonymous Mode.

Xen0Man Tuesday, December 3, 2019 at 6:31:21 PM EST in response to somebody stating VPN is enough:

Mmh not really... Anonymous mode is meant to be used together with VPNs. It blocks libtorrent advertising facts about you. For example, client's fingerprint (in peer ID) or user-agent.

You should never disable anonymous mode, unless you want to connect to some private trackers that uses the peer ID and user agent to identify white-listed clients.

you’ll likely find your upload/download speeds are slower, mainly because DHT & uPnP are typically disabled

If anonymous mode was disabled for a public tracker, are having DHT & uPnP still enabled dangerous? And what if qbittorent is bound to a network interface (the VPN), wouldn't all qbittorent data still have to passthrough the VPN regardless?

I kind of get that uPnP can open up ports without user intervention, but I've seen VPNs offer specific ports during connection so I'm not to worried about that.

OS doesn't matter. And windows with crapware removed runs just as well. (OMG, there is so much crapware on the barebones install)