1Сникам никогда не приходит в голову читать документацию по программам, которыми они пользуются.
Starting in Firefox version 98, when you download a type of file that can be opened with an installed application, you can set Firefox to always open similar files:
- Right-click the downloaded item in the Downloads panel. (You can also do this from the Downloads Library.)
- Select Always Open Similar Files from the context menu.
Selecting Always Open Similar Files will add a new entry to the General panel Applications section of Firefox settings, to use the system default application to open that type of file. You can later change the download action (see above) to a different action, such as Always ask or Save File, if you wish.
https://support.mozilla.org/en-US/kb/change-firefox-behavior-when-open-file