Apache module proxy_html not working

I have a Joomla 4 site running in a Ubuntu 22.04 server (hostname = web-02). The Internet facing web server running in a Ubuntu 20.04 server (hostname = web-01) has configured as a reverse proxy for several applications. Both servers run Apache2.4. In web-01, the VirtualHost's config is like this:

<VirtualHost *:443>
...
ProxyPass       /site2 http://web-02/site2
ProxyPassReverse    /site2 http://web-02/site2
...

From outside, when I call up https://{real-domain-name}/site2/, most contents appear OK except the site's logo. Upon inspecting the HTML I noticed that this is due to a wrong URL:

   <img loading="eager" decoding="async" src="http://web-02/site2/images/headers/logo.gif" alt="xxxxxx" width="760" height="117">

On the web-01 I have enabled, among others, the following Apache2 modules

proxy, proxy_connect, proxy_html, proxy_http, rewrite

If I go inside web-01 and do wget http://web-02/site2/ The resulting html file shows the wrong URL: http://web-02/site2/images/headers/logo.gif

If I go inside web-02 and do wget http://localhost/site2/ The resulting html file shows the wrong URL: http://localhost/site2/images/headers/logo.gif

So Joomla got the full URL from the $_SERVER variables and this is something I cannot change.

But in the end, how on earth did http://web-02/site2/... appear in the first place? Isn't that what mod_proxy_html is for?

I figured out with reference to Using ProxyHTMLURLMap to redirect css and js requests The new configuration is like this:

<Location /site2>
    ProxyPass       http://web-02/site2
    ProxyPassReverse    http://web-02/site2
    ProxyHTMLEnable     On
    RequestHeader unset Accept-Encoding
    ProxyHTMLURLMap     http://web-02/site2 /site2
</Location>

Unset Accept-Encoding is needed, thanks to https://stackoverflow.com/questions/40683850/apache-proxying-leads-to-err-content-decoding-failed-error