So, I'm trying to set up gluetun. I linked a Firefox container to it and apparently every check of DNS leaks shows that it's leaking. Cloudflare and quad9 are the servers, the same names that I've set to dot providers. So I am gathering from all of this that these leaks are to be expected? And non of the DNS servers show my real IP, always one of mullvad IPS. Am I getting this right?

I honestly can't get my head around this. I have a machine with Linux (endeavouros), and docker with a few containers. Since I want all the traffic from this system to go through the VPN, do I need to set up gluetun? I think not, but I am not 100% sure...