Camera Monitor has a button that jumps to the stock Camera app. It needs a shortcut, set up once — here is why, and how.
iOS does not let one app open the Camera app. There is no public way to do it: Apple exposes no address for Camera, so no app can send you there directly. What apps are allowed to do is ask the Shortcuts app to run a shortcut — and a shortcut is allowed to open Camera. So Camera Monitor asks Shortcuts, and Shortcuts opens the camera.
CamMonitor Camera.The name has to match exactly, including the capital letters — that is how Camera Monitor finds it. It is deliberately not called “Open Camera”, so it cannot collide with a shortcut you already have.
On the camera screen, tap the camera button in the top-right corner. The first time, Camera Monitor explains this setup; once you have the shortcut, tick Don't show again and the button goes straight to the camera. You will pass through Shortcuts on the way — that flash of the Shortcuts app is the mechanism working, not an error.
The zoom and aspect ratio do not carry over. Camera Monitor cannot hand its settings to the Camera app; iOS provides no interface that accepts them. The button opens the camera, nothing more.
If the shortcut is missing or named differently, Shortcuts sends you back to Camera Monitor and the explanation appears again. Check the name against CamMonitor Camera — a trailing space is the usual culprit. If Shortcuts itself has been removed from the device, reinstall it from the App Store.