How to make sure transmission is using my vpn?

I have transmission running on my server in a docker container that is supposed to go through gluetun. If I run test with ipleak and other torrent ip testers it shows my vpn's ip address. However transmission is running way faster download speeds than deluge or qbit were with the same configuration. It makes me wonder if all the traffic isn't going through the vpn somehow and I can't think of any other way to check things other than ipleak tests. I'm probably being over paranoid but a few months ago qbit leaked and I got a letter from my isp. I really don't need that happening again. Any help would be appreciated.