This mod is great and is pretty much essential. However, if the player wants to join a server with enforce-secure-profile, it's currently impossible to do so. I've already seen a warning screen being mentioned in the issues, and I propose that this mod (or a companion mod if this isn't in scope for this mod) provide an alternative chat system, preferably a standardised one.

How this would work is that the user would be warned that the server uses enforce-secure-profile and that their messages could be used to report them, and if the user chooses to continue, the chat message box would have the ability to send messages through the regular Minecraft chat protocol, or any other protocol (Matrix? IRC?) and messages wouldn't arrive at the server at all, preventing any message from being reported. More importantly this would let users communicate through a system that is... well just better than Minecraft chat.

Drawbacks

• This would require every user that would like to participate in chat to use the same mod, otherwise messages wouldn't be seen by other players.

Good things

• If a standardised instant messaging protocol is used then non-Minecraft clients would also be able to connect, and cross-server communication would be possible

Questions

• Would this be in scope for this mod? This mod already disables telemetry, doing more then what it's initially intended purpose was. Therefore it's entirely normal for such a feature to be included in this mod.
• Would this require a name change for the mod if it is implemented? In my opinion, yes.
• If this isn't in scope for this project, could this be implemented as a companion mod for this mod? This makes more sense then implementing this feature in the mods current state, however if the scope of this mod is widened then this feature could also be included in this mod.

If this is feature request is greenlighted I'm more than willing to contribute to the implementation of this feature.

I didn't mean to imply a centralised chat system, just any chat system (preferably standardised, not as in centralised but as in it has a standard for it). This could be encrypted text through the regular chat system without spamming other people's chat boxes with mess (it is possible to encode text or any data in zero-width invisible characters), however the medium, protocol, etc. are all implementation details. The point I tried to make was that a way to completely bypass the report system by just not sending regular text messages would be cool

Your idea assumes that the mod is installed on both client and server. But when that is the case, why would the server want to enable enforce-secure-profile at all? That makes no sense...

Edit: I re-read your message and I think you meant like a centralized chat system that does not depend on the server the player joined. I think that is very much out of scope and creates confusion.
Why would people want to talk to random strangers instead of the players in the same server?
Even if the chat servers were created per game server, why would people want to talk and get messages from a small segment of players in that server? Imagine not being able to talk to your teammates in a minigame...

If anything like your idea could be implemented, I'd suggest opt-in encrypted private messages that still used vanilla chat system.

I definitely like the idea of having the means to chat with players in secure way that does not put the task of relaying messages on game server, but this is definitely out of scope for this mod, at least for now. Even if we go easier way and host our own external third-party service that will be used to relay messages instead of trying to make everything P2P - making the end product convenient to use and well-integrated with vanilla is a big task. This mod disables telemetry because it can be disabled with a single well-placed mixin, but your idea will take way more than that.
Maybe it can be merged into the mod once it is properly developed, tested and widely used, but it will have to start as a separate project.

I think you could also implement an end to end encryption system. For the server and players without this mod the messages would be garbage and could not be used as evidence in a report. I am not sure how much effort this would be to implement but it should be easier than an external chat server.