Slack's separate sign-ins for each space is strange to me. On a new install, I can't log into my account and automatically be connected to every space I'm registered to.
Coincidentally I was invited to Slack for user testing a couple years ago. They asked me to sign into slack and as I was going through that said, "you know what's really annoying? When I do this now I have to sign into each workspace." When I signed in, a list of available workspaces appeared.
Turns out I was a user tester for exactly that feature.
That's weird. For me, I still need to log into every single Slack workspace separately.
Most of them redirect to app.slack.com, however they have no visibility into each other. So it's several browser tabs kept open and left running in the background on those days.