I’m using Firefox as well and it’s the same in Chromium for me. Interestingly, on my mobile phone, the text next to the KDE logo is not an svg but plain text instead. Thus it is not cut off in any way.
Viewing the svg in Inkscape, it is noticeable that some part of the text is not on the canvas.
After looking into the svg again, I think now I see the problem.
The font set in the svg is ‘Noto Sans’ which I’ve installed on my desktop but not on my phone. That’s why my phone uses a fallback font instead.
So the text just has to be set to the font we want and then converted to a path so the font can’t change depending on the fonts installed on one’s system, right?
Wouldn’t it be better for the sake of accessibility to have it set to the system’s font, though? The font can be served by the webpage anyway, so conversion to a vector graphic shouldn’t be necessary whatsoever.