Seems like this might be possible? https://github.com/retrooper/packetevents/blob/8aeef01bd4223c52322a44d3ceb44bcec5a3a388/api/src/main/java/com/github/retrooper/packetevents/protocol/chat/message/ChatMessage.java#L41

That takes a boolean. I'm talking about changing the text.

Seems like this might be possible? https://github.com/retrooper/packetevents/blob/8aeef01bd4223c52322a44d3ceb44bcec5a3a388/api/src/main/java/com/github/retrooper/packetevents/protocol/chat/message/ChatMessage.java#L41

That one is for messages, not popup tho?

Edit: this is what popup uses https://github.com/retrooper/packetevents/blob/2.0/api/src/main/java/com/github/retrooper/packetevents/wrapper/play/server/WrapperPlayServerServerData.java#L108

That takes a boolean. I'm talking about changing the text.

I'll tinker with it tomorrow, if you find something earlier feel free to PR.

Unfortunately, I'm pretty certain the text is clientside.

The client just displays the insecure popup to itself if that boolean is false.

ChatMessage is an unrelated class, that's to do with actually sending a chat message.

Haven't seen anything concrete about the text being client-side, but I clearly misinterpreted that class. Thank you both.