Fixing Firefox's Time Confusion

The Problem I am re-evaluating Firefox as my everyday browser (moving back from Brave) and was reminded of the Multi-account container functionality today. That is a killer feature, IMHO. I’d been running several instances of Brave under different profiles to keep things separate, but this is so much easier (and better with RAM, maybe?). However, I was also reminded of an incredibly annoying and frustrating side-effect of Firefox’s now-default privacy feature to prevent browser/device fingerprinting: the timezone for my device is mis-reported to websites, so the displayed timestamps of messages are off by hours....