Is Google Sign-In allowed for account registration on pornography websites?

Hello,

I discovered a pornography website that uses Google Sign-In (OAuth 2.0 / OpenID Connect) to allow users to create new accounts.

I would like to know whether Google permits its authentication services to be integrated into websites primarily providing sexually explicit content.

If this violates Google’s OAuth policies or other applicable terms, where should such usage be reported?

I would appreciate clarification from Google or someone familiar with the applicable policies.

Thank you.