As of 5.0 the content browser is introducing behaviors that directly interrupt some workflows.
1 - First, there seems to be no way to force the content browser to always be a floating window anymore : it always ends up reverting to the new “slide up” behavior. I do understand that the very oddly named “Dock In Layout” button allows to undock it and move it to a legacy-style location in the UI (in my case making it (temporarily) floating, as that is how I use the CB) ; but if one decides to have it as floating and then closes it, recalling it again later (as was previously done by clicking the relevant icon in the top bar, and now done by ctrl-spacebar) makes it slide up again.
(Pelase note that I am ignoring the option to bring up one or more CBs by navigating the top menu as this is not a viable option during a work session and doesn’t solve the issue anyways).
2 - Secondly, UE relies heavily on selecting an item in the content browser (for instance a material) and then clicking the left-pointing arrow in the details of an asset to link things up. This has been like that since forever, and this is of course still the case in UE5. However, if one selects an asset in the new fancy “sliding up browser”, then undocks it (by clicking the oddly name “Dock” button 
) to make it floating, then the selection gets lost and needs to be performed again.
These two regressions are significant and are in no way compensated by the dubious benefits of the new “sliding up” behavior. Both CB styles (legacy and slide up) could absolutely be made to work elegantly together with a set of toggle options, but at this time they do not. Therefore it would make sense to either get this fixed as soon as possible, or reverted to the pre-UE5 design which was objectively more flexible.
Of course I could very well be missing some hotkey, in which case please let me know.
Lastly, some advice to whoever is in charge of UE5 UI and UX : while I do appreciate the use of text instead of cryptic icon-based buttons, said text should describe the action that the button actually performs as opposed to one of the two possible outcomes that can happen after clicking on it Because now you have button that can either dock or undock a panel … called “Dock” I am not sure if you mean Dock the noun or Dock the verb, but regardless of intent this is really quite confusing.
And at the end of the day no one should have to repeatedly perform this “undocking” operation dozens of time per session anyways, as it is unfortunately the case now for users preferring a floating CB.
I hope this makes sense !