PNG and SVG at a glance
PNG is a raster format: a fixed grid of pixels, compressed without losing any detail, with an optional alpha channel for transparency. Enlarge a PNG beyond its original size and the edges turn soft and blocky, because there are no extra pixels to show.
SVG describes shapes as paths in a small text file, so it stays sharp at any size and can be recoloured in Figma, Illustrator, Inkscape or with CSS. Converting a PNG traces areas of similar colour into those paths. It redraws what is already in the image; it does not add detail that was never there.