PAT Lifecycle Management Create API Returning 401 Unauthorized Error

Hey Everyone,

Hope you all are doing well,

I am trying to create an Azure DevOps Personal Access Token via PAT Lifecycle Management API to utilize Work Items API but I am getting 401 unauthorized Error.
Here's the curl request -
curl --location 'https://vssps.dev.azure.com/mayankaggarwal9919/_apis/tokens/pats?api-version=7.1-preview.1'
--header 'Content-Type: application/json'
--header 'Authorization: Basic [Redacted]'
--header 'Cookie: VstsSession=%7B%22PersistentSessionId%22%3A%229e3cefcb-0bf3-42cb-b3e3-9c76748cb94d%22%2C%22PendingAuthenticationSessionId%22%3A%2200000000-0000-0000-0000-000000000000%22%2C%22CurrentAuthenticationSessionId%22%3A%2200000000-0000-0000-0000-000000000000%22%2C%22SignInState%22%3A%7B%7D%7D; X-VSS-UseRequestRouting=True'
--data '
{
"displayName": "new_token",
"scope": "app_token",
"validTo": "2023-12-01T23:46:23.319Z",
"allOrgs": true
}
'
I tried passing the token in different formats like API Key, Basic and Bearer just to hit and try but getting the same error for all of them, Any insights will be highly appreciated.

Best,
Mayank