According to the HomeKit guideline, the manufacturer's app can’t control HomeKit settings.

If you just turn on/off the camera in the eufy app, the function in eufy app will be turned on/off immediately but it won’t affect the use of the Home app, in which the camera needs streaming, recording, and detecting properly. So, if you want to turn on/off the camera completely, you should turn on/off the camera both in the eufy app and the Home app.