What they rolled back was charging claude -p "..." and use of Claude Code as an ACP agent at API rates. But the use of OAuth2 authentication with their subscription plans still feels at least risky: https://code.claude.com/docs/en/legal-and-compliance#authent... (granted, the wording is anything but clear).

Whether and under what circumstances they actually enforce this these days, I do not know. Regardless, if your preferred harness does not support that authentication flow (which most don't), then it doesn't really help you even if you could. For what it's worth, I do not consider the Claude Code ACP adapter an adequate solution.