Microsoft debuted the "ribbon interface" back in 2007 to give Office a fresh new look to compliment its new features. Many complained it was counterproductive much like the former assistant present in office releases before 2007 (who doesn't remember clippy?), but honestly, it wasn't bad looking from a design standpoint. The fresh new design was the only thing that made me like it.
Going on that, in 2017, LibreOffice, the most popular open source office suite alternative ever since Oracle destroyed the forever loved OpenOffice, has also implemented its own take on the ribbon interface. However, while I'm no designer, it's not hard to tell from comparisons that not only have they implemented a functionally worse interface, they also did a splendid job of making it one of the ugliest by maintaining the pre-office 2007 design elements. Like please, using classic win32 tab controls instead of actually making it a "ribbon interface"? There's not even a little padding in the tabs? It's all crunched together.
Granted this is still "experimental", and the theme extensibility of some linux desktops does make it more tolerable, but let's be honest here, nobody in the ~1% of Desktop Linux users actually want this. Please, if you're going to invest this much time into it, at least make it look better in Windows, the platform that debuted this with the user base of pretty much the only users who will actually (maybe?) use it. Otherwise what's the point of wasting so much time on it?