Problem:
Resize PNG and SVG markers for a better quality. On mobile view, the PNG marker is displayed pixelated.
Solution:
I checked it and the SVG markers are always resized to 32x32
There's a workaround to avoid it. You'll find the code line that controls this at line #565, in the file: "/toolset-maps/resources/js/wpv_addon_maps.js":

var scaledSize = new google.maps.Size(32, 32);

You could change the size value in the actual plugin file if needed, but since this part of code is not filterable, it is not possible to change it with a hook for example, you'd have to edit the file itself. ( please note that you'll need to keep track of this edit, as future plugin updates will overwrite any changes )

I also checked that PNG files are shown in the map with the same size they've been uploaded, it is necessary to work with the image and upload the final version to use it.