1SE needs permission to use your camera, microphone and photos, and your iPhone sometimes resets these. To check them, tap your profile picture at the top left of the home screen, then the settings icon at the right, then Camera and Media > Manage Permissions.
This will take you to your phone's settings for 1SE.
Check that Microphone, Camera and Media & Apple Music are turned on, and that Photos is set to Full Access.
If everything is on and it still doesn't work, turn the permissions off and back on.