VCS integration with Gitea fails with http 404

Hi, I`m having issues integrating gitea to YT
For this conversation, let`s say I have the following setup

YT server = https://tracker.mydomain.net:3337/ . It runs in a custom-built docker-container, on my NAS, Youtrack 2023.1

Gitea server = https://git.mydomain.net:3003/ . It runs in a custom-built docker-container, on my NAS, gitea 1.19.0

In gitea, I have the following org: "docker", in that org, the following 2 repos: "devicelist" and "hostmanager". The corresponding projects and org have been created in YT

Now, when I want for any of these projects to add a VCS integration, I get stuck with an http 404 error. I've entered the following info:
Server type : Gitea
Repo URL : https://git.mydomain.net:3003/docker/devicelist/

Personal token : as generated from Gitea

In advanced settings, I've copied the repo URL from above, and I've imported the JKS from my internal SSL repo.

Now, as soon as I click SAVE, it refuses to proceed and shows in red: HTTP 404.

I know that the repos exists on git, of course. It's not a DNS/connectivity issue as from the YT container I can telnet on gitea's container at the proper port (telnet git 3003).

It must be a very simple thing that I've overlooked ?

<br>Updated : further tests<br>
I've added the following to the end of my gitea's app.ini:
```
[webhook]
ALLOWED_HOST_LIST=*
```
Restarted the gitea server, issue still present. I get this in the logs

```
$IP_ADDR - - [08/Jul/2023:10:29:28 -0400] "POST /docker/devicelist/api/v1/repos//hooks HTTP/1.1" 404 9300 "-" "YouTrack/2023.1 (build #11071). Base URL: https://tracker.mydomain.net:3337" "-"
```

Also, the gitea server is behind an nginx reverse proxy (also in a docker container on the NAS). Please note that there is no proxying issue between a client, nginx and git, as other webhooks work just fine.