Arch Linux

Description:
Firefox has a growing number of privacy-invasive features being turned on by default. The latest one is a nearly full-screen popup ad for their paid VPN service: https://old.reddit.com/r/firefox/comments/13ro31o/mozilla_sends_popup_ad_overlay_in_firefox/

I'd like to propose we append a few safer default settings to the existing vendor JS file in the package() function:

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// Disable unreleased experimental changes
pref("app.shield.optoutstudies.enabled", false);

// Normandy allows Mozilla to change the default value
// of a preference for a targeted set of users
pref("app.normandy.enabled", false);

// Disable ads on new tabs
pref("browser.newtabpage.enabled", false);

// Use a blank page on startup instead of one with ads
pref("browser.startup.homepage", "about:blank");

// Disable pop-up ads for Mozilla's VPN service
pref("browser.vpn_promo.enabled", false);

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Additional info:
There are many more about:config tweaks (pocket, safebrowsing, more telemetry, etc) that could be considered for security and privacy improvements: https://github.com/arkenfox/user.js/blob/master/user.js

The very short list of suggestions proposed in this bug report are meant to introduce absolutely no risks and be an objective privacy improvement for all users.