Thanks for inquiring Aspose.Slides.
I have worked with presentation file using Aspose.Slides for Java 17.4 on my end and have generated the PDF file using following code. I have not been able to observe quality issue in exported PDF and for your kind reference, I have attached the file as well. Can you please observe the output and share your feedback if there is still an issue.
String path=“C:\Aspose Data\”;
Presentation pres=new Presentation(path+“example of pictures wmf.pptx”);
pres.save(path+“example of pictures wmf.pdf”,SaveFormat.Pdf);