Fix late join & observe to de-admin admins. (#28319)

Content.Server/GameTicking/Commands/JoinGameCommand.cs

@@ -1,7 +1,10 @@
+using Content.Server.Administration.Managers;
 using Content.Server.Station.Systems;
 using Content.Shared.Administration;
+using Content.Shared.CCVar;
 using Content.Shared.GameTicking;
 using Content.Shared.Roles;
+using Robust.Shared.Configuration;
 using Robust.Shared.Console;
 using Robust.Shared.Prototypes;
 
@@ -12,6 +15,8 @@ namespace Content.Server.GameTicking.Commands
     {
         [Dependency] private readonly IEntityManager _entManager = default!;
         [Dependency] private readonly IPrototypeManager _prototypeManager = default!;
+        [Dependency] private readonly IAdminManager _adminManager = default!;
+        [Dependency] private readonly IConfigurationManager _cfg = default!;
 
         public string Command => "joingame";
         public string Description => "";
@@ -67,6 +72,12 @@ namespace Content.Server.GameTicking.Commands
                     shell.WriteLine($"{jobPrototype.LocalizedName} has no available slots.");
                     return;
                 }
+
+                if (_adminManager.IsAdmin(player) && _cfg.GetCVar(CCVars.AdminDeadminOnJoin))
+                {
+                    _adminManager.DeAdmin(player);
+                }
+
                 ticker.MakeJoinGame(player, station, id);
                 return;
             }