Recently, I've noticed that my Minecraft server's MOTD was suspiciously switching to my subservers' MOTD if I connected to my subserver and then quit. This was more noticeable if there was a network issue that caused the client to disconnect, due to Minecraft not automatically refreshing the server list.
But how? This is impossible! The Status Response Packet can only be sent if the user is in Status state, not in Play state!
Or perhaps, it ain't impossible since Server Data Packet's introduction in Minecraft 1.19.
Why it exists? While I'm not sure, I think it is related to Minecraft's new reporting system, because it is used to show the infamous "Chat messages can't be verified" toast.
Since BungeeCord dd3f820, the packet is now parsed and blocked on BungeeCord's side, so this is already fixed in newer BungeeCord/Waterfall versions, yay!