Prevents the client from removing deleted messages (until restart).
Use ".message.NoDeleteMessages-deleted-message .markup" to edit the CSS of deleted messages.
This plugin is trusted to not contain malicious code, but is unofficial due to it being banned from the BD servers due to conflicting beliefs between BD mods and me.
Create an issue at https://github.com/Mega-Mewthree/BetterDiscordTrustedUnofficialPlugins for support.