Automatic download
Can firefox ask what I want to do with files, like pdf-s which I want to open, not save / download.
Wšě wotmołwy (2)
Version 98 made that change. https://www.mozilla.org/firefox/98.0/releasenotes/ There is a preference you can change but it will only have a temporary effect. https://support.mozilla.org/en-US/questions/1370494
Try changing the action to "Always ask" in the Applications list on the Settings page. This article will get you there: View PDF files using Firefox’s built-in viewer.