Google's John Mueller said when it comes to PDFs on your site, you don't have to worry about the core web vitals scores or if they are mobile friendly. John said on Twitter "Yeah, we essentially ignore PDFs when it comes to Core Web Vitals & mobile-friendliness. Sometimes they show up in the reports, but there's no need to do anything specific with them."
Here is that tweet:
Yeah, we essentially ignore PDFs when it comes to Core Web Vitals & mobile-friendliness. Sometimes they show up in the reports, but there's no need to do anything specific with them.
— 🍌 John 🍌 (@JohnMu) July 15, 2021
Now, yes, they can show up in the reports, as this Google Webmaster Help thread shows PDFs listed in the report (click to enlarge it) - hat tip to @PeterNikolow:
But you don't have to worry about PDFs ruining your page experience scores if your site lists tons of even a few PDFs. You will be okay, so relax.
Forum discussion at Twitter.