While this isn´t a new update from facebook, it is a recurring topic frequently mentioned on the internet. When trying to evaluate your site performance, you are checking the sources of your traffic. Sources of traffic are important when trying to decide which channels to use for your advertisements.
In your sources you will find links such as facebook.com, or m.facebook.com, which are fairly straight forward. Facebook.com is your normal desktop traffic from facebook, and m.facebook.com are mobile users. Sometimes you will also find the l.facebook.com as a source in Analytics, and wonder what the „l“ stands for.
Facebook lets their users create custom vanity URL´s, which are unique web addresses, branded for marketing purposes. For Facebook this means, that the page-, or username will be displayed in the url. Having a vanity url often helps with visibility – being able to be found in the internet.
Due to data-privacy regulations, facebook is not allowed to pass on personal information such as the username to third parties. A URL such as mine facebook.com/viviensara.fechner, is turned into l.facebook.com in Google Analytics to protect my personal information.
Your mysterious l.facebook.com sources in Analytics are encoded vanity urls from facebook.