While not a show stopper, have been finding it annoying and disruptive not knowing why cmnd+ will support zooming in when previewing a .pdf, and other times that function is not supported.
That can be confusing so here is an example.
I see an icon of a pdf, hit space bar and decide I want to zoom in w/o opening in preview.
This function is super convenient yet only appears to work some of the time. Why?
PDFs sitting in the exact same directory, even, where some zoom and others do not. PDFs sitting on the MacOS Finder desktop, some zoom others do not.
While PDF is a commonly supported format, two PDFs which look identical could be different with one created in Microsoft Word using text, tables… The other could be JPG images of each page saved as a PDF.
It’s possible that the way the PDF was built and from which source have a bearing on how it behaves.
In my experience the small version happens when the file is on a cloud and hasn’t been downloaded locally yet. Usually waiting a minute and trying again will result in the big version. Opening the file and then closing and previewing it invariably allows for the bigger previews