Double path in url (in redirects)

I added more details to this issue: https://gitlab.com/gitlab-org/gitlab-ce/issues/38973

So I installed GL on kubernetes using helm, everything seems to work as expected but after each action (like saving settings or retry a job) I got a 404 becuase the URL has a duplicated path, ex: https://x.y.z/group/repo/-/jobs/52/group/repo/-/jobs/52/trace.json?state=

GL is running as only http (external_url is http) but load balancer (haproxy) listen in both (http/s) adnd redirect http to https when neccesary. There is not any other reqrtie or redirection in haproxy side.

This issue is very annoying as constantly need to go back to get out of the 404 (notice the actions that triggers this issue are successful anyway) also it prevent some features to work (like console output in CI)

Any clue will be very welcome as this is driving me crazy