I went into the page permissions for page. I see a Motion Sensor setting that is set to Allow (by default). I recommend this option turned off by default or ask.
Steps:
- load a local html page on file://
- go to javascript settings chrome://settings/content/javascript
- click on the disclosure icon. that takes you to brave://settings/content/siteDetails?site=
- go to motion sensors
the motion sensor is turned on by default.