Hi pod.sc1, where do you see that option?

There definitely has been a change in how Firefox handles PDF downloads. This article describes the updated behavior and viewing options: View PDF files using Firefox’s built-in viewer.

Is that what you were looking for? If not, could you describe the problem in more detail.

There is a pref on the about:config page to control this new feature.

• browser.helperApps.showOpenOptionForPdfJS = false

You can open the about:config page via the location/address bar. You can accept the warning and click "I accept the risk!" to continue.

• https://support.mozilla.org/en-US/kb/about-config-editor-firefox