After seeing a team of fedi software developers drop their Matrix bridge to their Discord after the total lack of moderation tooling resulted in an extremely transphobic spam wave, I for one am not surprised.
Another team also dropped Matrix, but went for Zulip instead, which is also open, but more collaboration oriented a la Slack rather than community oriented like Discord, which probably would not fit what the group in the OP is looking for.
cows_are_underrated@discuss.tchncs.de 3 months ago
Same. Matrix is great.