First, send feedback to Google about this from within the system settings. If it doesn't bother you that much, I would just sit tight until the next update to see if it gets fixed. If it does bother you, then the main troubleshooting step I can think of would be to clear the app cache/data for Pixel Launcher in the Settings>Apps menu. This will wipe your homescreens clean, meaning you'll have to set them all back up again. But hopefully this will fix the missing icon.
EDIT: Oops, I posted that before your latest response. What if you re-update the Camera app?