Yes, the US' ambiguity has been slipping a little bit of late, but it still compatible with their long-term held position. The US has consistently (over decades) both not recognized PRC sovereignty over Taiwan, while also not recognizing Taiwanese independence.

However, US actions have also been clear. In 1996, the US sailed a carrier battle group right down the straits when things get testy. The US has been selling weapons to Taiwan for decades. The US has enacted export limitations against one country, but not another.

Functionally, this action did not declare war on China. Yes, China leadership could find a way to stretch this into "war", but they also could have stretched any of the other things the US has recently done (including Biden straight up saying that the US would intervene if China invaded).