I was using Evernote Legacy 7.14.1 for the longest time, and noticed the same thing occurring here after the Ventura 13.3 update.
From everything I was able to piece together, it appears that 13.3 changed something with the ability to preview the embedded PDF files - possibly the removal of Apple deprecated code (in Ventura) that the older versions of Evernote were still using somehow.
It unfortunately isn't a plug-in that can be downloaded, but moreso how older versions of Evernote were coded to use some legacy Apple plug-in to display the PDF contents inside the note.
The latest version of Evernote (10.55.2) does not have this problem - however, the ability to create private local notebooks was lost way back when (the main reason I continued to use Legacy). I had to subscribe just to migrate my old local notebooks into this latest version. (free version caps the data upload limit to about 60 MB per month - I used that up in less than 5 minutes...)
If you export each of your Evernote notebooks into a .enex archive (they will still retain the embedded PDF data), I've found that you can do one of the following:
Import into Apple Notes - pretty straightforward, but I've found that certain notes (with no rhyme or reason) will not display the PDF within the note. I have to double-click the embedded PDF which will open in Preview to view the document.
Import into Joplin - https://joplinapp.org/ - it's a free open-source note editor similar to Evernote, can import straight from .enex archives. The only drawback is should you decide to move back to another editor (Notes, Evernote), it's a little convoluted to export notes created here for these other programs to smoothly import.
Best advice - keep your .enex files backed up somewhere. Like me, you may need these again...
