@peanut-butter 

Hi,
1. The camera has inserted some English notify voices and can be triggered by some actions, such as when the SD card is formatted or recognized by the camera. Did you hear what the camera said?

2. On the Tapo app> Me> View Account > Login Security > Login Activity page, you can check if there is a new device logged in to the Tapo app with your TP-Link account. And you can enable the 2FA feature to protect your TP-Link account.
Making Your Account More Secure: Introducing Two-Step Verification (2FA) for the Tapo App
 

3. Some cameras do not support the feature to turn off the Camera Account option. On your Tapo C200, you can click on the Account Information to check if it asks you to create a new camera account or if you have configured a camera account. If you have created a camera account before, change the account to protect your camera.

Best Regards

  @peanut-butter 

Hi,
1. Please go to the Tapo app > Me > Third-Party Services > Amazon Alexa and Google Assistant page to check if you have linked your camera to Alexa or Google Assistant.

2. On the Me > Device Sharing > Tapo C200 page, please check if you have shared the camera with other people.

Typically, with your current settings, and if the camera is not shared and linked to a third-party device, no other person can stream and talk to the camera. If you still hear the voice from the camera like someone is speaking through the camera, I hope you can pay attention to what it says. I think the camera is speaking some built-in notify voice.

Best Regards