how come it reads the power data of the Garmin running Power app
Not sure what you are asking. Can you provide more information regarding your issue and/or suggestion?
I use the Garmin connected to the zwift run, I installed the Garmin running Power app it works perfectly but I see that it has an end to work zwift does not detect the given thing it does with styrd instead
Currently Zwift Running does not use Run Power from Stryd. If you want this information you will need to use your Garmin watch or the Stryd app.
It is possible in the future Zwift will incorporate Run Power but no official announcement on that. Running is still dominated by HR and Pace instead of Power so I am not expecting Power to make its way into the running side until it becomes more widely adopted like it is in the cycling side.