In late 2018, Facebook began appending "fbclid" query strings to the ends of all outbound URLs originating from Facebook's site. These URLs take the format &fbclid=IwAR0Ylspg9Zo1-4JLuy5L3N7RhNTHg5BETDMlsQkUST8QC1JCo3iC6-54_PQ, and are appended to all outbound content, both FB ads as well as organic posts. This post will show you how to remove this parameter from your Google Analytics reports.
This fbclid parameter is similar to GA's UTM strings, which are used for campaign attribution. However, while UTM strings are generally used at an aggregate level, the fbclid is a click ID with a unique value for each user. Facebook uses it to connect user actions on a website with the Facebook ad or content that they engaged with.
In Google Analytics, this new parameter has the undesireable side effect of cluttering the All Pages report with unique URLs. Normally these URLs would be rolled up together into a single line, but the unique fbclid causes each link to show up as a distinct value.
Fortunately there's an easy fix: simply navigate to Admin > View Settings and enter 'fbclid' into the Exclude URL Query Parameters box.
This will strip out the fbclid parameter from the URL, and enable these URLs to display as a single line again, as before. It won't affect your GA or FB reporting, as this setting only affects how the URL displays in GA. Note that this setting isn't retro-active, and will only change data going forward.