Firefox will not open local HTML files

I’m using Manjaro Gnome. After the stable updates of Aug 28, Firefox (version 79.0-1 from the Manjaro repository) will no longer open any local HTML files in my home folder. Invariably, after 3 minutes the tab crash reporter screen appears. How can this be fixed?

As a test, on another computer running Manjaro Gnome and before doing these updates, Firefox (same version) has no problem opening local HTML files. Since Firefox is not being updated in this set of updates, it seems the problem is created elsewhere in the updates?