Same problem here - the top portion of every image is corrupted (in one of several forms - black and white static, coloured lines, pure white, etc) upon a high quality (for print) PDF export.
See attached (I've drawn on the red arrows).
Loaded Macbook Air M2 with Monterey 12.5.1, Affinity Publisher 1.10.5
Using the a low quality "Digital small size" preset works fine, and if I take the files back to my ancient (intel/High Sierra) mac and do a full size 400 dpi export there, that also works fine (and how I was able to send this magazine to the publisher!).
Tried a delete/reinstall like Lisaaa and this didn't fix the problem.
Darryl