macOS Tahoe upgrade causing 'Apple could not verify' error for PDF files in Preview

Hi. After the Tahoe upgrade I get the error; "Apple could not verify {pdf file name} is free of malware that may harm your Mac or compromise your privacy." The only remedy is to set Adobe Acrobat Reader as the default App then it is possible to right-click and choose Preview. It is cumbersome and quite annoying. Please advise how to remedy this new problem.

[Re-Titled by Moderator]

Original Title: After Tahoe upgrade, I am facing issue with Preview and the opening of PDF files especially when Preview is the Default PDF App