Build-in Ghostscript conversion unexpected behaviour

When generating a plot directly as png, the font appears slimmer than expected. When generating a plot as PostScript and then export it to png using the macOS Preview App everything is as expected. Please see the zoomed in crop below:

Comparison between direct png and ps -> png

The upper text appears slimmer while the lower text appears meatier and is the expected outcome.

The upper example is done via gmt begin … png while the second one is done via gmt begin … ps and then exported to png from the macOS Preview app. The difference is subtle on screen but quite noticeable when printed. GhostScript 9.50 was used. I suspect some different antialiasing handling when rasterising the plot.

Has anybody experienced a similar problem and found a solution for it?