Thank you for your asking. Kindly provide the information below so that we can better assist you.
1. Model Name: Settings>System>About phone
Refer to the link below to check the model name by model no. in the linkhttps://www.asus.com/support/FAQ/1014441/
2. Your current firmware version
Settings>System>About Phone>Software information
If you try to update to the latest version, does the issue still persist?
3. Does the issue appear after any system/apps' download or update?
4. Does the issue appear on the stock camera only or on other camera apps (e,g. Instagram) as well?
Please try clearing cache & storage of Camera (long press "Camera">App Info>Storage & memory>Clear cache/Clear storage), then try to re-install 3rd party camera apps and check again.
5. Also, please try "the Factory Reset"
Settings>System>Reset options>Erase all data(factory reset)
Please note that once the Factory Reset is completed, all data, apps, settings and personal information will be deleted.