Preview.app PDF export as image resolution bug

If I open a PDF File in Preview app on macOS Big Sur and try to export it as image file at any file format such as JPEG, PNG, HEIC or TIFF, the resolution settings don't work. No matter what resolution I choose, I always get a file with 72 pixels/inch.

This bug exists till macOS Big Sur and I have no knowledge that Apple is working on it to fix it.

Does anyone know a simple workaround for me in the meantime?

I actually want to create a JPG file out of a Pages document.

Unfortunately Pages don't let me export to JPEG directly, so I'm used to convert it first to PDF and then with Preview.app to JPG.

I know that the Keynote app is able export as images, but the documents are created in Pages and can't be opened in Keynote. Also Acrobat Reader requires paid Pro version to do what macOS did for free in Catalina and previous versions.

P.S. Why is 72 pixels/inch the default setting anyway? Thought we all have retina displays now…