It has visual class libraries that give LO a slightly different look depending on what you're running it on. I'm typing this from a Debian system running KDE P

It has visual class libraries that give LO a slightly different look depending on what you're running it on. I'm typing this from a Debian system running KDE Plasma, and my LibreOffice reports using the gtk3_kde5 VCL. It uses Qt5 widgets and looks, for the most part, like a regular KDE Qt5 application. It no longer looks or feels like a Java application. Because it's not - Java is optional except in LibreOffice Base. You can disable JRE in the options, and LO parts that are not Base will retain nearly all functionality.