We need to think about it some more. In general our policy is to not require applications to be changed for them to be used as a snap, so we’ll try to preserve that in this case as well. At the same time, this is a pretty unfortunate behavior from Firefox for several reasons, some of which may be better understood in this super long thread coming through many years: https://bugzilla.mozilla.org/show_bug.cgi?id=69938
Quick workarounds:
- Save the file in $HOME/Downloads or similar, instead of trying to open it directly from /tmp
- Change the location in the TMP environment variable with which Firefox runs