LibreOffice are working on a NotebookBar: https://wiki.documentfoundation.org/Development/NotebookBar which is very similar in looks and functionality to what OnlyOffice has to offer.

Can confirm, was about to write the same exact thing this very minute. Lest this gives the impression of a "Me too!" post, I wanna mention that this also happens in the Epiphany browser. (No idea when this occurred for the first time, I installed it just this morning.)
Ikey mentioned earlier in the thread that the glitch isn't Firefox-specific, so I don't know whether this warrants a new ticket.

FWIW, this runs flawlessly as a stand-alone release, or whatever you want to call it. Been running it for years without having the slightest issue.

Had the same issue. Installing the suite doesn't let the user do anything. One has to pick Writer, Calc, (those 42kb or so packages) etc. additionally and individually in the Software Center.