Hey, Alondra!
Thanks for stopping by the Apple Support Communities. It looks like one of your third-party social media apps, Snapchat, is suddenly asking for permission to access your Camera. We're happy to help!
Typically, the first time you open an app like Snapchat after downloading it to your iPhone you will be prompted to allow access to the camera and microphone. If you allow this, there shouldn't be a need to re-allow the access in the future, though occasionally sometimes that may occur. If so, heading into Settings > Privacy > Camera should allow you to re-enable the access: About privacy and Location Services in iOS and iPadOS - Apple Support.
If you are not able to grant Snapchat access to your camera under the Privacy settings, you can reset your privacy settings by going to Settings > General > Reset > Reset Location & Privacy: Return iPhone settings to their defaults - Apple Support. Then, the next time you open the app you should be asked to allow access again.
If that does not work, you can also delete the app: How to delete apps on your iPhone, iPad, and iPod touch - Apple Support then redownload it: Redownload apps, music, movies, TV shows, and books - Apple Support, which should trigger the request upon opening the app after reinstallation.
Best!