I think that’s a real concern. If we consider moving to something else (again), element.io is pretty nice (and free for opens source communities)
We do have our trusty old Slack too though I have heard good things about Matrix/Element
… but Zulip has a much smarter interface that’s closer to how people interact in real life: in a room you have conversations that you can focus in on or zoom back out to see the other conversations going on.
Zulip - Wikipedia written in Python too
Threads in Slack are so so and Discord doesn’t support them at all. I really hate Discord 
Anyone interested in testing Zulip with me?
The Plone Discord server doesn't require such verification.
Verifying that you're not a child is only required where the content is not for children. This isn't a concern for the Plone Discord server.
Well Discord actually supports threads and can also have a forum like organization if needed.
I'm not here to defend Discord at all, I don't like the idea of sending IDs and such but if it's not actually needed I would not be concerned. Also I would be a fan of moving again, if avoidable.
We have used Zulip at University of Jyväskylä for some five years now. Run it on our own server. It is by far the best modern chat tool available, easily surpassing anything Slack and Discord have in terms of chatting. Threaded conversations focused on topic are just the best.
It is missing video calls though.
The FSF uses Jitsi, so we could set one up too, though of course we are back to deciding whether our admin team should manage services. Zulip self-hosted plus Jitsi self-hosted. Or Rocket (Slack clone) self-hosted. I dislike being the product (of for profit companies like Discord) and I dislike being subject to age or identity verification laws.
It seems that, for now, Discord has backed away from its plans because of the backlash, but it doesn't mean we can't revisit the decision. As the main character says in the Shrike trilogy, "Choose. Then choose again". 
You really need to see how Zulip does it. Discord's threads are a worse UI experience than Slack's, and Slack's isn't as good as Zulip's.
"Discord is delaying age verification checks for a little while after its plan inspired a lot of hand-wringing among the community. But it's not backing down."
I’ve been maintaining our Zulip server since the beginning at the university. The official installation method requires dedicated Debian (or similar) server. They do publish container images for Zulip, which I have been using with Podman. They renewed their container installation method recently and have up to date instructions for it. The updates have been rock solid and well automated.
I’m sure Plone would also qualify for free service from Zulip’s cloud service: Zulip for open-source projects. In-fact I think somebody has already made plone.zulipchat.com.
I understand why it would make sense to move to an open solution and it might actually be true that we can apply for the free cloud service.
I just want to add another point to consider: several people already have Slack running on their machine on a daily basis and a good subset of these people also have Discord because of other communities, so it could feel like a burden to have to add a new one.
We still have plone.slack.com which was initially used by a small number, mostly for teams, and its use grew when we hosted the online Plone conferences in 2020 and 2021 (it was the chat service to go along with the video streaming provided by loudswarm.com)
Yes, that was @jean and I some years ago.