I am in search of an official OCM discord server because i would like to have a list of servers which use OCM.

Maybe you can create some channels, where users can write in their minecraft server. You could create a "minigame" channel, a "citibuild" one and so on.

I personally would like to explore other minigame servers which are in use of the old combats.

There is no official discord server for OCM. I believe @rayzr522 runs a discord server where you might find other people using the plugin.

my server is no longer around, unfortunately (closed due to inactivity and my diverging interests)

Can you send me an invite link?

Sorry but it seems we don't have a discord server.