Why?

Sometime channel was flooded with lots of join/leave or death message cuz of poor connection/getting killed continously. A setting for automatically delete those messages with a timeout like DiscordChatChannelListCommandExpiration is quite useful (and still keep track of server activities by not disable them at all)

What and How?

Add a new options: messageExpiration in message.yml's MinecraftPlayerJoinMessage, MinecraftPlayerLeaveMessage, MinecraftPlayerDeathMessage or even MinecraftPlayerAchievementMessage that its value is -1 (disabled) by default. Server owner can set the timeout by seconds.

Are there alternatives?

I don't know.

Checks

• I have used the search at least once to check if my idea has already been suggested and perhaps already implemented.

Anything else

No response

Users will still got notified of a new unread message in that channel even if the message is delete due to a Discord limitation

I think it still ok according to server owners' preferences