OSX Preview works incorrectly

Your profile shows you are using macOS Sequoia v15.5. That is the official naming now as Apple stopped referring to the operating system as OS X several years ago.

There is no assurance that Apple's Preview will be compatible with a PDF generated from an unknown PHP PDF library (e.g. FPDF, etc.). No one here can fix Preview.

Here is a test that may rewrite the PDF internals in a more favorable manner that allows Apple's Preview to open and display the entire PDF:

1. Get Firefox 140.0.4 or later and this assumes that it will be installed on the macOS 15.5.
2. Open your PHP generated PDF in Firefox.
   1. Does the PDF display as you expect?
3. Save the PDF from Firefox to your Desktop with a different name (e.g. foo.pdf)
   1. Doing so will flatten any annotations preventing future annotation editing
4. Open the newly saved PDF in Apple's Preview to determine if it now opens and displays all pages

OSX Preview

OS X is outdated by almost a decade, so it would not be surprising if its Preview version cannot cope with more recent PDF documents.