I recently upgraded from High Sierra to Big Sur, skipping the intermediate versions, because I needed to run new software that would run under HS. One thing I discovered is that in Safari, it no longer puts the Favorites under the URL window for any new Safari window. This is extremely inconvenient for me as I often used those shortcuts directly from the window I was in. Now it appears you can only invoke them from a brand new window, and only if you tell Safari that you want new tabs to point to the Favorites page, which is also filled with useless things like Safari suggestions and reading lists I don't want there. While it's true that the Favorites are available from the Bookmarks menu, it's also true that they are uselessly down at the bottom and not at the top where they would actually be handy.
When I upgraded, I had several Safari windows with multiple tabs open in each one. After the upgrade, the primary window no longer had the Favorites below it but the other windows did. New windows all open in the same manner as the primary, without the Favorites. This tells me it is possible to still have them there, I just don't know how to make them the default. Please help me, thank you, it is driving me nuts.
If you have not tried this already, try it.
Safari > View > Show Favorites Bar
Show the Favorites bar: Choose View > Show Favorites Bar. A bar with your favorite websites appears below the toolbar.
Thanks, that was it!