if you look closely at the raised letters you'll notice where the etchant was able to undermine the mask. This brass plate was made using old technology, today many people are using laser toner for the mask.
Print on glossy paper then using an iron to transfer the toner.
There are of course better commercially available products.
https://i.postimg.cc/N02n4DFf/20200913-140456.jpg
https://i.postimg.cc/fLfQcCqS/kvva.png