Really curious, what paragraph of the ToS is being violated?

https://venturebeat.com/technology/anthropic-cracks-down-on-... don't have the paragraph, but here's the news about it for you.

Look it up. They have banned people over this and it was all over the news, some people cancelling their accounts etc

So the same is true if people use OpenCode with Claude Pro/Max?

Yes only the plan OpenCode themselves sells is „legal“ Opus.