Authentication issue on ApplyProvisioningTemplate with PnP.Framework and Site.Selected permissions

Hi,

I may found have a strange issue related to Site.Selected permissions and applying a site template via PnP.Framework.

My setup:

1. I registered an AAD app with Site.Selected permissions and role = fullcontrol
2. I grant access to this app on a SharePoint site
3. Then I connect in C# to this SP site:

var cert = new X509Certificate2(Convert.FromBase64String(_configuration["AppPermissions"]), string.Empty, X509KeyStorageFlags.MachineKeySet);
var authManager = new AuthenticationManager(
   "MYCLIENTID",
   cert,
    "MYTENANT");

using (var context = authManager.GetContext("MYSITE"))
{...

4. Then I load my template and apply it

var dir = AppDomain.CurrentDomain.BaseDirectory;
XMLTemplateProvider sitesProvider = new XMLFileSystemTemplateProvider(dir, "");
ProvisioningTemplate provisoingTemplate = sitesProvider.GetTemplate("TemplateMid.xml");
web.ApplyProvisioningTemplate(provisoingTemplate);

5. Then I get an exception with an 'Access is denied.'
6. After some research I found out that the template works fine when I remove the language settings.

<pnp:SupportedUILanguages>
   <pnp:SupportedUILanguage LCID="1031"/>
   <pnp:SupportedUILanguage LCID="1033"/>
 </pnp:SupportedUILanguages>

7. The strange thing is that it works when I apply the template (with the language settings) via PowerShell

Connect-PnPOnline -ClientId MYCLIENTID -Url "MYSITE" -Tenant MYTENANT -CertificatePath .\MYCERT.pfx
Invoke-PnPSiteTemplate -Path .\TemplateMid.xml

Start with the C# ApplyProvisioningTemplate call and the XMLTemplateProvider loading TemplateMid.xml, focusing on the SupportedUILanguages section and the Access is denied exception under Site.Selected permissions. Compare this path with the working Invoke-PnPSiteTemplate PowerShell flow; done means the C# template application succeeds with both language settings and the granted permissions.