Can't check much of it now, but one thing that concerns me in Discord, and that I've already seen happening, is entire chat histories getting nuked, either by accident or by moderation's dishonesty. With AT Protocol's middleman-style of delivery system, I don't trust it for preserving a chat history, but with ActivityPub and its nature of more easily being self-hostable, backing up suddently becomes far more reachable. So for that, I'll be waiting until ActivityPub compatibility is added.

Also, on a more positive light and pondering on design possibilities, I wonder how channels will look like for platforms not inherently compatible with such. Maybe Mastodon and Misskey will treat as private mentions? Also maybe Lemmy and Mbin will treat each channel as a separared DM? Also makes me wonder about other platforms within the fediverse. 👀