Getting "Unable to complete authentication for user due to looping logins" while making an api call through postman to azure

I am trying to fetch ticket using azure api, but it's showing "Unable to complete authentication for user due to looping logins" while making an api call, i have passed proper Authorization header and provided correct personal access token in base64 encoded.(see fig)

I am using GET https://dev.azure.com/{organization}/{project}/_apis/wit/workitems/{id}?api-version=1.0 for making an api call. link: https://learn.microsoft.com/en-us/rest/api/azure/devops/wit/work-items/get-work-item?view=azure-devops-rest-6.0

am i missing something? Looking for suggestion.

On Postman, to execute RESI API using PAT (Personal Access Token) as the authentication, you should set on Authorization tab, instead of directly on the Headers tab.