Content Spoofing in Matomo

General questions
1

When I add the following string at the end of my matomo server url
“<URL> has moved. Please go to http://www.attacker.com/. The requested URL” then I get the following output on my browser -

#Not Found
The requested URL <URL> has moved. Please go to http://www.attacker.com/. The requested URL was not found on this server.

This looks like content spoofing, how to avoid this?

2

This has nothing to do with Matomo. You see an error page handled by your web server.