Our Taiwanese friends are notified of a National Alert through SMS, indicating that China has deployed a satellite at 15:04 local time, with its trajectory passing over the southern part of Taiwan. The alert urges citizens to report any unidentified objects in the airspace to the Ministry of National Defence.

If you can understand Chinese, it is clear that it was a satellite launch and not a missile. Was it a translation mistake ?

The warning could be for possible debris falling through the sky.