Firefox 97 has the latest evolution of the combined preview/setup/print experience introduced in Firefox 84. The old code has been removed. There's no going back.

Calling Print should show the preview on the left side -- see sample screenshot attached. Is this not working for you?

There are now several posts about this on the new feedback site connect.mozilla.org (which has replaced mozilla.crowdicity.com). You can access this new site using your Firefox login. I would encourage anyone who has an opinion about this to visit the new site and leave some feedback.