Mozilla has added five new flags to Firefox’s about:config settings page. Firefox 60 is expected to be released in May 2018. The Proximity and Ambient Light APIs are now disabled by default by default. The two flags will be available in Firefox Nightly and Firefox 60. Privacy expert Lukasz Olejnik argued that these two APIs could be abused by attackers and advertisers. Mozilla’s decision to disable access to these two API is a result of concerns over privacy concerns. The new flags will ship enabled by default, but users will have to manually enable them.
Source: https://www.bleepingcomputer.com/news/software/firefox-gets-privacy-boost-by-disabling-proximity-and-ambient-light-sensor-apis/