Make sure that port forwarding is actually working - on ProtonVPN the port allocated to you can change regularly and QBittorent’s settings need to be updated accordingly. Easiest way to check is to click through your active torrents and check if any peer has the I
(incoming) flag.
If you have not set up something like this, port forwarding is probably not working: https://github.com/mjmeli/qbittorrent-port-forward-gluetun-server
I would personally just run the plain script as a cronjob on the host though, to not rely on some random docker image.
There’s a difference between source available and open source. For example, actually being allowed to distribute modified versions is pretty damn important: