48 page full colour document created in Pages

I have a 48 page recipe book I created in Pages. The finished size is 800MB. When I go to export & save to create a pdf, the downloaded size is 4.2GB. The file is too large to download to my printers server. I tried creating the pdf through the print option but that doesn’t work. Adding to the mystery is that this is the second book I’ve created in Pages. The first book was 784mb. The same set-up (48 pages with full colour photos). I had no problem creating a pdf (through export & save option) of the same size and the download to my printers server. The only difference between the two files is that halfway through creating the 2nd book I upgraded from the iPhone 13 to the iPhone 15. Any suggestions would be very much appreciated. All the photos were taken with my cell phone and air-dropped to my iPad.