This is already an essential mod, but I think it would be more convenient to use if it were also made as a serverside plugin for use in bukkit/spigot servers, since not all players are aware of this change even existing, let alone caring enough to change their settings over it.

Spigot and its derivatives already remove cryptographic signatures from chat messages, making chat reporting impossible. On Spigot / Paper, this mod is not necessary.

Depending on their implementation (which I'm not familiar with) messages might still be selectable for reporting, which, ideally - they shouldn't be. I am no plugin developer, but I'll pin this for future reference and discussion.

Looks like someone have made it after all: https://www.spigotmc.org/resources/noencryption.102902/

I will keep NoEncryption as a reference in project description until someone makes an agreed-upon optimal solution.

There's also another plugin — No Chat Reports - Spigot — that is more feature-complete, as it retains vanilla functionality (such as multi-language support) that is otherwise apparently broken with other plugins like the one mentioned above.

There is now a wiki with instructions: https://github.com/Aizistral-Studios/No-Chat-Reports/wiki/Protecting-Server-Players