qBittorrent won't attempt to find any I2P peers unless you add I2P trackers to the torrents. After that it's hit or miss similar to public torrents.

These are working public trackers in I2P that I know of:

http://w7tpbzncbcocrqtwwm3nezhnnsw4ozadvi2hmvzdhrqzfxfum7wa.b32.i2p/a

http://opentracker.skank.i2p/a

http://opentracker.r4sas.i2p/a

http://opentracker.dg2.i2p/a

This tracker is also in I2P but it only tracks torrents registered at their site:

http://tracker2.postman.i2p/announce.php

only i2psnark, but i2psnark is an awful client.

Agreed. On the upside it's been around much longer for torrenting within I2P so I suspect a lot of I2P users just have that set up for torrenting purposes and that's how it's been for years.