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

Since Brazilian daylight savings time rules changed, in places in Brazil where it was used, Slack Desktop in Windows or Mac is showing the wrong time (advanced 1 hour).

When I change slack timezone to a place where daylight savings doesn't apply following their info (Salvador for instance), in some places of the app the hour is shown correctly (eg. notifications), but on slack rooms they still show up wrong.

How to fix this?

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.