Discord
Some meetups occur on Discord, but you can't participate with the web client, you have to use the "app" (sigh). However, when I tried to install discord on Debian bullseye, it failed.
sudo dpkg -i discord-0.0.15.deb
sudo dpkg -P discord
Then I found this which fixes it! It still didn't install smoothly, but it works!
sudo apt install libgconf-2-4 libayatana-appindicator1 libc++1
sudo apt --fix-broken install
sudo dpkg -i discord-0.0.15-bullseye.deb
Now I have a working Discord in the Applications -> Internet
menu and a little Discord icon in the top tray when it's running.