Apache Reverse Proxy using mod_proxy - django

Question

0 Introduction
I'm trying to setup a server with a main website hosted on ports 80 and 443 (let's call it example.com) and a section on this website that serves umami analytics hosted on port 3000 (let's call it umami.example.com) using a reverse proxy.
I'm using Django and Apache (with mod_wsgi as hinted from the django project) and I have to setup DNS using Cloudflare.
The main website works as intended, redirecting http traffic to https (more on that on the Apache section) and I'm tring to add this section under umami.example.com but every request ends up in a 404 error given by my main website.
Currently I'm trying to make the umami part work using a reverse proxy (as shown in the first section of the Apache Config)
####################################################################
1 DNS
DNS are configured using Cloudflare with 3 A records:
example.com -> server IP address
umami -> same server ip
www -> again same ip
and some MX and TXT ones.
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2 Apache Config
<VirtualHost _default_:80>
ServerAdmin admin#example.com
ServerName umami.example.com
ProxyPass "/" "http://127.0.0.1:3000/"
ProxyPassReverse "/" "http://127.0.0.1:3000/"
</VirtualHost>
<VirtualHost *:80>
ServerName example.com
ServerAlias www.example.com
Redirect permanent / https://example.com/
</VirtualHost>
<VirtualHost _default_:443>
ServerAdmin admin#example.com
ServerName example.com
ServerAlias www.example.com
Alias /static /mainfolder/static
DocumentRoot /mainfolder/django-folder
<Directory /mainfolder/django-folder/static>
Require all granted
</Directory>
<Directory /mainfolder/django-folder/django-app>
<Files wsgi.py>
Require all granted
</Files>
</Directory>
WSGIDaemonProcess django-folder python-path=/mainfolder/django-folder python-home=/usr/local/env
WSGIProcessGroup django-folder
WSGIScriptAlias / /mainfolder/django-folder/django-app/wsgi.py
Include /etc/letsencrypt/options-ssl-apache.conf
SSLCertificateFile /etc/letsencrypt/live/example.com/fullchain.pem
SSLCertificateKeyFile /etc/letsencrypt/live/example.com/privkey.pem
</VirtualHost>
####################################################################
3 What I've tried
Connecting directly to the IP address bypassing the DNS (port 80) makes no difference.
Connecting directly to the IP address bypassing the DNS (port 3000) works as intended.
Swapping places on the Apache Config works like this:
When the reverse proxy comes first (the config is as posted) then connecting to the 80 port serves the analytics website.
When the redirect comes first (swapped) connecting to the 80 port redirects to the HTTPS website
Adding and removing ProxyPreserveHost makes no difference.