How to make Slack work with new Brazilian daylight savings time information?

The key is to change also the computer clock to a different timezone where daylight savings doesn't apply (Salvador, for instance), and refreshing Slack (Ctrl+R did the trick for me)

Obs1: You don't need to be the slack admin to do this, it's related to your individual machine settings.

Obs2: Even if your time is showing correctly on your machine with your timezone set to Sao Paulo, for instance, slack will show incorrect time. You must set to a location with no daylight savings information, such as Salvador. Slack apparently uses that info instead of the current machine time.