The bot is supposed to delete the original message that player sends in discord and then sends the same message back to discord from the bot. Are you saying the original message isn't being deleted?

Looks like it, also the DeathNotes lines are being put into Discord chat:

BOT vandaag om 03:05
<color=#87CEFA>[NSA] Riddle</color> killed <color=#FF8C00>[NSA] Riddle</color> using a <color=#C4FF00>F1 Grenade</color>.

You gave your bot full admin access? If not you will need to give you bot permission to delete messages in that channel.

DiscordDeath handles death notes not this plugin so you should change it's config for which channel you want the messages to go to. It looks like the built in umod formatter isn't removing the tags properly so there will need to be a DiscordCore update to fix that.

I mean the DeathNotes plugin in Rust: https://umod.org/plugins/death-notes
These in-game notices also goto the Discord chat

No sweat, if the tags get removed, then it's OK.

I just pushed an update to DiscordCore to fix the tags issue.

DiscordChat plugin doesn't output DeathNotes data. You would only get output if you installed the DiscordDeath plugin which is meant for DeathNotes.