how to get full resolution from Photo on Mac

The info window in Photos shows 4800 x 3200, the exported file is 1086 x 724 at full size. Export of unmodified original is 4800 x 3200.

How are you checking the size of the exported image?

Try to revert the image to the original in the Edit panel, then try again to export the edited version. Does that make any difference?

And make the same test n different Photos Library, located on your system drive. perhaps your Photos Library needs repairing. You can create a new library for testing by launching Photos while holding down the options key, until you are seeing the library chooser panel. select to create a new library. Import a few photos, then test exporting.

Sorry I have no idea - based on your answers that should give you a photo with the original pixel dimensions and it does for me - either you or I are missing something as that should give you what you see in the Photos info window

LN

What editing have you done on the image? Any cropping?

What are all the export setting

LN

What does the info window in Photos say the size is? Where are you seeing these 1086x724 dimensions? What do you get if you export the unmodified original?

LN