The new tag window version, previously called the "Experimental Version" will become the default and maybe only tag window version in the future. It takes a little while to get used to it, and needs some configuration to feel comfortable with it, I find. But it is configurable, so that is good.
The new tag window was made the default for a couple of versions, so it would be the window that displayed when you clicked "Tag" in the Action Window area. That change has been reverted for now, but you may not be seeing that change yet.
Anyway, Shift-Click Tag will give you the old version.
BTW, Search is your friend.