HI,
I detected an issue regarding pdf files and Preview app so submitted a ticket with Feedback app. Here is the answer received yesterday:
As a result of your feedback, there are changes in the latest update, build 23A5286g, that have resolved this issue.
You can see the software build your device is running and check for the latest update by clicking on the Apple logo in the upper left hand corner > About This Mac. If the build is not visible, click on the macOS version, e.g. 10.15.x, to reveal it.
Has this issue been resolved after installing the latest update?
Feedback ID FB12303791, Preview app won't open some pfd's
Do not reply to this email. Please login to Feedback Assistant to let us know if the problem is fixed for you.
I have to check later today if the issue has been fixed.