Preach brother.
Companies like Tuxedo Computers and System76 try to pass themselves off as hardware companies, but I think it's fair to say that they actually have more in common with software companies, in that their work is mainly to do with software and clever marketing and very little in, say, designing the board that goes into the machines they sell. Not to say they don't touch hardware at all and are just playing the slimy middle man; they obviously put in some work but definitely not to the extent implied by the marketing.
One of the most telling sign that Tuxedo Computers isn't what it seems on the surface is that their laptops sometimes will have weird non-Linux-compatible hardware despite claiming to be a "made for linux" hardware vendor. Take for example, the Sirius 16. At first glance, it's a system that seems almost perfect for Linux: Amd CPU and GPU so no need to wrestle Nvidia drivers. Great, right? But then you look at the fingerprint scanner and, hang on, it's "Windows only". Why is that a thing on a "designed for Linux" laptop? It's because Tuxedo didn't design this thing. Some other company did. And they sure as hell didn't design it with Linux users in mind. If they did, they would probably have used a fingerprint scanner that's compatible or dropped that feature it all together to make the product more affordable (it's a gaming laptop; how much do you need biometrics?). The fact of the matter is that barebones laptop manufacturers (Clevo, Tongfang, etc.) design for the average market, OS-wise. In other words, they design for Windows. These machines can run Linux, just as HP and Dell and Lenovo and Acer machines can run Linux, but there's no guarantee that they will run Linux flawlessly.
Oh yeah, and their manuals are very sad, if not pathetic. Dell, the soulless beast of a company that it is, still pumps out detailed service manuals for all of its laptops. Lenovo manages much the same. So does HP.
So, yeah, maybe people should take this into consideration before buying from a Clevo reseller like Tuxedo or System76.
I had the same problem. It's been a while but I'm fairly certain the problem can be solved by installed the appropriate integration package. Try installing these packages,
libreoffice-plasma
libreoffice-qt5
libreoffice-style-breeze
. Take a look at this forum thread for more info, https://discuss.kde.org/t/libreoffice-does-not-honour-kde-theme/3347