How can I change whether I share Apple Health App data with the Start TODAY app?

You can change your permissions to share certain Apple Health App data with the Start TODAY app by following the steps here:
https://support.apple.com/en-vn/guide/iphone/iph2b3a37ddd/17.0/ios/17.0#iph6ed63de2d

Alternatively, go to your Settings, tap on Health, then Data Access & Devices.