Linked image blurred after export to PDF

[Nadiidea]

Hi!

I'm new here. I was doing a design for a wall sticker. I inserted a linked images and there's also some vectors elements in it as well.

My problem here is, after I exported it to PDF/Jpeg, only the linked images came out blurry. The other vector elements are just fine. FYI, the image I use is a high resolution image. Really appreciate it if anyone can help me with this. Thank you in advance.

[Doug A Roberts]

What is the size of the exported PDF, the size (in pixels) of the linked image, the effective PPI of the linked image in Illustrator, and the downsampling PPI setting in your PDF preset?