The Unified Interface remove the universal search bar at the top. It's only one extra click but it's inconvenient to have to click on the search button now, wait to be brought to the search page, then select the type of search you want to do. There's lots of space for it since the breadcrumbs have been removed, why not use all of the available space at the top of the screen to make the interface easier to use especially for users with slow access.
Ideas Administrator

Hello - Thank you for this feedback. We have a new search experience with a ton of usability and core searhc improvements, one of which is a global search bar in the page header. This is currently an opt-in feature. Here is the blog post that you can review: Introducing the new search experience in model-driven Power Apps | Microsoft Power Apps