Tor Browser 9.5 includes important security updates to Firefox. Users on desktop will be able to opt-in for using onion sites automatically whenever the website makes them available. Website publishers can advertise their hidden services to Tor users by adding an HTTP header that can suggest visitors switch to the version of the site that is published using the Onion service. Tor Browser also introduces Onion Authentication to allows admins of Onion services to add an extra layer of security to their website by setting a pair of keys for access control and authentication.”]
Source: https://securityaffairs.co/wordpress/104234/deep-web/tor-browser-9-5.html