Python requests: 401 on /oauth/token with Client Credentials

Trying to grab an access token via Python requests for our OTel tracing pipeline. The auth call keeps failing with a 401, even though the client ID and secret match our integration settings.

response = requests.post(url, auth=(client_id, client_secret), data=data)

The payload includes grant_type=client_credentials. Checked the docs, seems standard. What am I missing here?