Depends on whether you mean the PRC’s idea of the policy, Taiwan’s, or most of the world’s “acknowledgement” of it, which means roughly “we understand what your position is and don’t publicly flout it while informally treating Taiwan as its own country.”
The PRC’s version, obviously no problem, Taiwan is part of China, they are China, the ROC is either illegitimate or an uppity province depending on your POV.
The ROC’s version, obviously not, because they are China, and the PRC is illegitimate, making this a blatantly hostile act. However, the ROC doesn’t actually insist on a One China policy anymore and is generally moving towards public acknowledgement of Taiwanese sovereignty, in which case this is arguably an act of war… But not one they can actually push back against.
Or, in other words:
Taiwan could make a big deal about this, but probably won’t, unless they do because otherwise the PRC will keep pushing boundaries and the world moves a little closer to a shooting war between China and America.