I have a Google Slides slide with two images, one on top of the other with the upper image being semi transparent. In Google Slides it looks good, but when I download it as pdf and open it in Mac's default program to see pdfs called 'Preview' the upper image is straight not even loaded. The same pdf opened in any browser looks good, with the upper image as it is supposed.
Link to the example reproducing the issue: Google Slides | Example
To reproduce just download it as pdf and open it in Mac's preview software