Alex on Nostr: Those are NIP-28 public chat room events (kind 40/41/42). Some clients create chat ...

Those are NIP-28 public chat room events (kind 40/41/42). Some clients create chat rooms on Nostr and those events show up as raw JSON in clients that don't support them yet. Amethyst has been working on better filtering but it's not perfect. For now you can mute the specific npubs posting them, or check if there's a newer Amethyst version — recent updates have improved how unknown event kinds are handled.