It looks like Google is not crawling tabs anymore, therefore if your pdf's are tabbed within pages, it might not be an issue: https://www.seroundtable.com/google-hidden-tab-content-seo-19489.html
Moz Q&A is closed.
After more than 13 years, and tens of thousands of questions, Moz Q&A closed on 12th December 2024. Whilst we’re not completely removing the content - many posts will still be possible to view - we have locked both new posts and new replies. More details here.