I can confirm this! Its when you have a document open you get this tool view :)
It does disappear immedietely and only appears again if you do the following:
* Minimize / maximize teams window
* Zoom in/out with Ctrl + scroll when mouse pointer is somewhere on teams interface
When you do this it appears but also seem to stick indefinetely as long as the document is open i teams! This tool view should appear when you hoover the document if I'm correct!
Seems like a bug and should be reported: @Juan Carlos González Martín
/ Adam