On March 16 2022 the OAuth Device Authorization flow will become an "opt in" feature for all OAuth and GitHub Apps. This change reduces the likelihood of Apps being used in phishing attacks against GitHub users.
If you own or manage an OAuth App or GitHub App that makes use of the OAuth Device Authorization flow, you should enable it for your Apps via its settings page:
The OAuth Device Authorization flow API endpoints will respond with status code 400 to Apps that have not opted in to this feature.