The US just doesn’t recognize China’s claims to areas (eg, Taiwan or ASEAN sea islands), so doesn’t regard those as Chinese territorial waters in the first place.

The point of US freedom of navigation exercises is to assert free transit of allied and international waters, despite Chinese claims, rather than to transit Chinese territorial waters. US warships generally avoid areas which the US views as Chinese territorial waters.

The fight in and around China's sea claims is they encroach into what the rest of the world generally agrees are other countries waters not international waters. The US would still insist it could travel through the Taiwanese or Phillipine waters China wants to claim as their own. It doesn't seem to map at all on to the situation between Finland and Estonia.