I solved this issue, so I write it down here in case anyone face the same issue. First of all, I think Traefik really wants to discourage ppl from using Ingress, so:
The logs do not provide the actual issue (even with DEBUG log), and it just returns 404
In the document, there is no clear explanation on how to do this configuration.
So, in my case, I need to do the following:
Deploy the Traefik Helm chart with the value "ports.websecure.tls.enabled=true"
Use "ingressClassName: traefik" in the Ingress, instead of the annocation, so the Ingress looks like this: