So Chinese bots are on lemmy too now. You obviously didn’t read the article - “Of those aircraft, the ministry said 10 had either crossed the median line of the Taiwan Strait, which previously served as an unofficial barrier between the two sides, or entered the southwestern part of Taiwan’s air defence identification zone, or ADIZ.”
In international relations, militaries have defined and at times unspoken rules of engagement. This was NOT routine flight over mainland China that you are making out to be, but was a clear breach of said protocols. Thus Taiwan sent its fighter jets to observe the Chinese military aircraft.