I'm no expert in #UI and #UX #design, but here's something that bothers me about Slack.

Why are there two menu bars for semingly related items? What makes unread messages ("Ungelesenes") and threads so special that it couldn't fit in the left sidebar (or vice verca), alongside the messages I saved for later?

More often than not I was looking for a menu item and had to look again in the other menu to find it.

This used to be better in the previous version of slack.