Version
90 of the Firefox browser is out. The headline feature this time
around, beyond working links in PDF output, is a new
version of the SmartBlock feature which appears to have been designed
with a specific goal in mind: “Third-party Facebook scripts are
blocked to prevent you from being tracked, but are now automatically loaded
‘just in time’ if you decide to ‘Log in with Facebook’ on any
website.“

Source: LWN.net – Firefox 90 released