They may be hidden. See the following from Organize the Home Screen and App Library on your iPhone - Apple Support
With iOS 14, you can easily hide pages to streamline how your Home Screen looks and add them back anytime. Here's how:
- Touch and hold an empty area on your Home Screen.
- Tap the dots near the bottom of your screen.
- Tap the circle under the page that you want to hide.
- Tap Done.
To unhide a page, repeat the steps above. Then use the App Library to quickly find apps hidden on different pages.