So I just installed build with new tabbed explorer and I do not know is it a bug or just poor design and quality assurance.
First and least problematic for now: the tabs are on the top of the window, just like in modern web browsers, but File explorer is not web browser – in file explorer you are meant to often tabs while also dragging files and folders and it is a bit unwieldy with tabs on top.
And it has (for now) menu bar that had to be dislocated and it looks weird and out of place.
They should have taken page out of many other file manager programs and put tabs in the main view or just above main view as it is case in MacOS and many Linux file managers.
The other issue is glaring white menu bar, across the middle of the file explorer in dark mode which is jarring at best. https://imgur.com/a/lDfCXNt
There is also a misaligned “up” arrow but at this point that is the least of all of their worries.