First time iPhone user here, some of my App icons on my Home Screen sometimes “blink” (turn to grey for a second), whats the meaning of it?
The app likely updated. When the app update is installing, the app is temporarily unavailable.
Alternatively, iOS may be cleaning the app. If your device is running low on space, iOS may delete temporary/cache data from the app’s container. This will temporarily make the app unavailable, for a couple seconds and show ‘Cleaning…’ in place of the app name.