Comment 8 for bug 1972762

This bug breaks any application that uses firefox to open local files in /tmp for display. I'd politely suggest that breaking this sort of widely supported and used functionality for no clear benefit or advantage is perhaps not the best design choice. This is especially true when users can simply go out and download other versions that do support this functionality but may suffer from not being regularly and automatically updated.

If the issue is security then having an about:config option to pop up a window for permission to open local files that defaults to ON might be a better solution which leaves warnings and functionality in the hands of the user (the feature could be turned off in settings or by accessing about:config) but defaults to a more secure option for those that will likely never intentionally open local files.