Sean Ross Callaghan has made an observation which I have not seen made anywhere else. First, there was an agreement under the Open Skies Treaty that actually allowed signatory countries to fly over the US and get an eye-full. Of course, everything would have been long covered up by the time the spook aircraft got over head. The idea expressed is that while China has not signed the Open Skies Treaty, Beijing Biden may have let communist China do a fly over anyway, perhaps as part of a deal. It is possible, but I tend to go with the idea that communist China is now so cocky that it is doing the provocation that it daily engages in with Taiwan, to its main enemy, the United States.
https://amgreatness.com/2023/02/07/did-biden-tell-china-to-send-the-balloon/