GGORG
Sounds to me as if you have set the GrapheneOS camera as default. Apps that access a camera use this default app.
To set GoogleCamera as default, first remove the GrapheneOS camera as default app via: settings>apps>see all apps. Tap on GrapheneOS camera>Open by default>clear default preference.
If you now open the camera via other apps/image picker, a dialog box should appear ("complete action using: Camera A/Camera B"). Select the GoogleCamera by taping on "always". GoogleCamera is now your default camera.
Regarding the similar icons:
I don't know which launcher you are using - but maybe you can just change the icon to avoid confusing them?
I sometimes use the KISS launcher - you can't change the icons there, but you can rename apps - instead of deactivating the GrapheneOS camera, you could simply rename it.