I am trying to add a customer header to web.config file in staging.pubxml, in VS 2022.

I get “The element beneath element is unrecognized”. What is the problem here or is there a better way?

<?xml version="1.0" encoding="utf-8"?>
<!--
https://go.microsoft.com/fwlink/?LinkID=208121.
-->
<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <PropertyGroup>
    <EnvironmentName>Staging</EnvironmentName>
    <DeleteExistingFiles>True</DeleteExistingFiles>
    <LastUsedBuildConfiguration>Release</LastUsedBuildConfiguration>
    <LastUsedPlatform>Any CPU</LastUsedPlatform>
    <PublishProvider>FileSystem</PublishProvider>
    <PublishUrl>C:Publish6StagingPRJ6PRJ6.Engine</PublishUrl>
    <WebPublishMethod>FileSystem</WebPublishMethod>
  </PropertyGroup>
  <configuration xmlns:xdt="http://schemas.microsoft.com/XML-Document-Transform">
    <system.webServer>
      <httpProtocol>
        <customHeaders>
          <add name="content-security-policy" value="frame-ancestors https://*.example.com https://example.com" xdt:Transform="Insert" xdt:Locator="Match(name)" />
        </customHeaders>
      </httpProtocol>
    </system.webServer>
  </configuration> 
</Project>