PDFs vs the Color Yellow (and Light Blue)

I don't understand why, but whenever I convert a Google Slide, Power Point, Word file with graphics, Mind Map etc. to pdf, anything with a yellow or light blue background comes out with no color. If the text is colored, then that too disappears.

This is the original Mind Map on mindmup.com

But this is what happened when I downloaded it as a pdf. Notice the light blue squares are now without color.

The solution is to download the file as a jpeg or png and then upload the graphic into Adobe Acrobat (best professional purchase of my career) or an online graphic-to-pdf converter like smallpdf, and convert it to a pdf. This way, the original colors are preserved.

The same thing happened when I tried downloading a Google Slide as a pdf, and it was crucial that the colors be preserved. I tried downloading it as a PowerPoint, but regardless of what I did (I even tried changing the shades slightly, using gradients, etc.) the pdf was missing the yellow on the yellow slide. I had to download the problematic slide as a jpeg and convert it to a pdf and delete the problematic page from the pdf presentation and insert the jpeg to pdf slide in its place.