With change to downloads (which seemingly happened with Firefox 98) a lot of people ask to return the old version of saving/opening files. For majority, this new system wouldn't affect a lot, but it seems there's enough of a minority to consider implementing an option in settings.
For those who don't know, before Firefox 98, each time you would download the file, you would be asked if you want to Open it or Save it. When you would open the file in this way (be it through Firefox itself, or via third-party app) file would be saved into Temp folder, a folder that stores temporary files that are deleted later.
The current implementation differs in that when you Open file it is instead saved to User's Download folder. This means that files must be manually deleted.
The current solution for those who prefer old method, is to open about:config, and change browser.download.improvements_to_download_panel to false. But this solution depends on both people knowing about this method and that Firefox Devs would keep that setting in the about:config. It also disables ability to set default "downloading preference" for files, instead showing download prompt every time.
I think Firefox should have a setting for Save location for opened files, here's how i imagine it:
Similar to Downloads setting, it would give several options, one of which must be true.
• Opened files are saved to the Downloads folder (which seems to be %userprofile%\Downloads) (default, as it is current implementation)
• Same folder as Downloads setting. (or alternatively, instead of doing that an option in a separate setting, put a checkbox under Downloads setting, something like "Save opened files in the same folder")
• Save opened files in the following folder (which is similar to Downloads setting's first option, which allows to specify a folder for files)
• Save to Temp folder (or %Temp%), where they will be deleted later (where files were saved when opened before Firefox 98)