Slack's app is two components. The first is the desktop app itself. The second is the web part, which can be updated separately from the desktop app. The releas

Slack's app is two components. The first is the desktop app itself. The second is the web part, which can be updated separately from the desktop app. The release notes for the app are talking specifically about the desktop app component. The fact that the web part can be updated separately is why you can hit ⌘R and have new features appear in your workspace. In my case, I quit and relaunched the (same version of the) desktop app and suddenly my sidebar looked different and I had a popup telling me that Slack was now faster.