Is this mode needed if you're using a VPN to hide your IP address? The page states only the following:
If you're using VPN, proxy or I2P, you probably want to enable Anonymous Mode.
What I would like to know is why the developer statement is true? And does it affect download/seeding speeds?
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.
I think it's generally recommended if you are security conscious to manually forward ports rather than allow uPnP to be enabled on your router. There's been cases where IoT devices or apps can open sensitive ports to your network without your knowledge. And the uPnP protocol itself was found to be flawed a few years ago: https://arstechnica.com/information-technology/2020/06/upnp-flaw-exposes-millions-of-network-devices-to-attacks-over-the-internet/
But you know, it depends on your risk profile. For most people, it's probably fine. Depends how paranoid you want to get.
Binding your VPN connection to qbittorrent is a good idea, for sure, if you use a VPN. I usually keep DHT enabled with a bound VPN connection and a manually forwarded port using Proton VPN. I'm going to try out anonymous mode to see if it affects speeds any, since it looks like it doesn't impact uploads or connections any more. That's a bonus :)