I figured it out, I'm using Firefox and tweaked the fingerprinting setting. This came back when I searched the web: timezone shifting can happen when you tweak the privacy.resistFingerprinting preference in about:config.
ziebelje commented on Dec 4, 2019
- Continue relying on
Intl.DateTimeFormat().resolvedOptions().timeZone;and moment to pick the correct time zone
- Do some moment configuration to set the time zone to the thermostat time zone
ke4roh commented on Feb 11, 2020
I’m going to recommend using the thermostat time zone. When I was in Germany trying to program my thermostat in North Carolina, it was a bit nuts. The Ecobee app wouldn’t let me set the times I wanted because they had already passed on my phone!