@Gu, Wenlong A Thanks for your patience on this. I have checked with App service Engineering team and sharing the below.
App service editor feature is in preview product and in recent platform updates run button is removed. 
These updates will take few weeks to roll out across all the stamps/regions. If you are seeing run button in some of the app then that is the reason for it.
Feel free to reach back to me if you have any further queries on this.