svg image looks grainy in LO impress

Hi, I noticed that imported svg images look “grainy” in LibreOffice impress (I mostly use this for equations). Unless I export the presentation as PDF, the quality does not look as good as it is supposed to be (both in normal and in presentation/slideshow mode). Any thoughts about why this happens? Do you have any advice? I’m using MacOS High Sierra 10.13.6 and LibreOffice Version: 6.3.1.2.