I recently bought a new iPhone, and migrated everything from the old iPhone. After confirming that the Pikmin Bloom app was working correctly on the new phone, I deleted the app and its data from the old phone. Because of that, iOS automatically removed Pikmin Bloom from the list of data sharing apps in the Health settings on ALL my iOS devices (two iPhones and one iPad).
On the new phone and iPad, Pikmin Bloom app warned me that the steps data was no longer syncing. However, all it did was showing me a Help article about giving the app permission in the Health settings, even though the app is NO LONGER in the Health settings. So I was stuck with no recourse until I deleted the app from all iOS devices and reinstalled it. Doing so added the app back to the list of apps in the Health settings.
It seems to me that the app only checks whether the Steps data is syncing, but doesn’t check if the app itself is still in the Health settings. FYI: all my devices are running iOS 27.