https://botkube-slack.herokuapp.com/ https://www.google.com/search?client=firefox-b-d&q=inurl%3Aslack.herokuapp.com and so on ...
What's the purpose of this heroku app ? Why not just use slack official : https://postgresteam.slack.com
I think some communities want a custom invite page explaining what the community is about. The official signin/signup page lacks any customization options.
(Both Heroku and Slack are owned by SalesForce these days. The Element project pre-dates those acquisitions)