Hi!, I understand what you are saying, I exported the file from Affinity in eps to send it to print in vector (because the print service accept it) and that it can be edited in another program, maintaining the highest quality without raster it. When I reimport it back into Affinity to see the result the lines look like this. I will have to be careful so that the design comes out as it was done in Affinity, but when you import it into another software like Adobe illustrator it looks good, and it's curious that the software where I make the illustration can't preserve it's self line style.
I think this is a problem, not because of me that I have noticed but because someone could share an illustration with another and that other could be use the Affinity suite and when reimporting it change these drawing finishes.