You can revert to the previous interface by setting a pref to false on the about:config page. print.tab_modal.enabled = false

By the way, which features are you missing in the new preview that you liked to use in the old preview? We've had questions about quite a few different details. For example: '''Simplify Page''' The "Simplify Page" checkbox applies the Reader View to the old preview. This is expected to return to the new preview in Firefox 87. Until then, you can click the Reader View button in the address bar to change the view then press Ctrl+p again. <img src="https://user-media-prod-cdn.itsre-sumo.mozilla.net/uploads/images/2021-02-19-13-48-19-8116ed.png"> You can adjust line spacing and font size using the Reader View toolbar: <img src="https://user-media-prod-cdn.itsre-sumo.mozilla.net/uploads/images/2021-02-24-12-41-26-52a667.png">