Getting this in my console:

Failed to call hook 'OnPlayerConnected' on plugin 'Rustcord v3.2.5' (NullReferenceException: Object reference not set to an instance of an object)
at Oxide.Plugins.Rustcord.HandleAdminJoin (BasePlayer player) [0x0003a] in <ee31b8ab85e74a018f76f6fdbd4f5583>:0
at Oxide.Plugins.Rustcord.OnPlayerConnected (BasePlayer player) [0x00025] in <ee31b8ab85e74a018f76f6fdbd4f5583>:0
at Oxide.Plugins.Rustcord.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x00e63] in <ee31b8ab85e74a018f76f6fdbd4f5583>:0
at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <b6af59acae274e5a94fb209dfc179b8f>:0
at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in <bae5f1223fce49c493b01571c99dce02>:0
at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in <bae5f1223fce49c493b01571c99dce02>:0

Specific player (admin)? or everyone?

Now that you mention it, it seems this message is popping up when one specific admin joins, not for anyone else.

Prolly something fucked with his name or something.

His name is "TheOgBrain".