I am also aware of the problem.
Currently, you can click on a PDF document embedded by better-pdf-plugin and you will land in the PDF on the page that was embedded. For this workflow it is necessary that the embedded element has the class internal-link otherwise obsidian is not able to detect the link itself.
This is where Page Preview comes in. It creates the popover for all classes of the internal-link type, which means as long as theres no possibility to tell obsidian that’s a link that should not create a page preview you have to live with it or deactivate the page preview plugin as workaround.
I also created a feature request for it. That introduces a way to address internal links without preview.