Google Search Console cannot read my XML: Sitemap appears to be an HTML page

I’m working on a web application written with AngularJS (v8) and deployed on an apache2 using proxy to forward requests (frontend, api, backoffice).

My problem is that I’m trying to submit the sitemap ({website}/sitemap.xml) on Google, but Google Search Console keep saying that it’s not valid: Google can read the link but it seem to be in HTML

gsc

My sitemap: sitemap

I tried to validate that XML on many website and I didn’t find any error.

I mentioned apache2 because maybe when Google try to fetch the URL, before finding the XML, apache give another page but I cannot prove that. I tried in many ways and the first page that I see when opening the URL is the sitemap and nothing else.

In my angular.json I added the file in the assets as follow:

"assets": ["src/favicon.ico", "src/assets", "src/sitemap.xml"],

What it can be?

Thank you