I think the bot used the websocket API and lemmy ended up deprecating that API. Because of this the bots don't work anymore.
Comradeship // Freechat
Talk about whatever, respecting the rules established by Lemmygrad. Failing to comply with the rules will grant you a few warnings, insisting on breaking them will grant you a beautiful shiny banwall.
A community for comrades to chat and talk about whatever doesn't fit other communities
Yeah, this is the reason. TankieReplyBot used Lemmy's WebSocket API because it was far more efficient for a bot to receive events as they happen rather than constantly checking for new comments and posts. With that gone, the bot will have to be rewritten to use polling instead, and the last time I did that, it caused my IP to be rate limited within an hour and that was with a relatively long polling interval.
That was my bot. Lemmy removed a feature the bot was using, so it stopped working.