> Saudi Arabia and Iran struck a peace deal this year, brokered with Chinese help.
It wasn't a peace deal - it was a normalization of relations (aka they've reestablished diplomatic contact) [0]. Iranian and Saudi proxies are still killing each other in Syria and Iraq.
> We haven't heard about Yemen since.
That's because of Oman acting as a mediator between the Houthis and Saudis [1]