Not entirely true. Google released Gemma 4 models recently. Allen AI releases open Olmo models. However, you're right that the Chinese open models seem to be much better than others - Qwen 3.* models especially are punching above their weights.
They released a single open model after being goaded by the community because everyone except "Open"AI were multiple generations into open releases.
We haven't heard a word since, I wouldn't be surprised if it takes them another 6 years to release their next one.