Matrix: https://matrix.to/#/#demofurs:foxyden.eu
IRC: irc://irc.furnet.org:6697/#demofurs
Discord: https://discord.gg/fDN6Ru2g8X

Also interesting
Demoscene Discord: https://discord.com/invite/MCDXrrB
barq group: https://barq.social/c/16MC6qV