The better fix

Author: Middledot

discord/bot.py

@@ -133,7 +133,7 @@ def add_application_command(self, command: ApplicationCommand) -> None:
             raise TypeError("The provided command is a sub-command of group")
 
         if command.cog is MISSING:
-            command.cog = None
+            command._set_cog(None)
 
         if self._bot.debug_guilds and command.guild_ids is None:
             command.guild_ids = self._bot.debug_guilds

discord/commands/core.py

@@ -1086,16 +1086,10 @@ def to_dict(self) -> Dict:
 
         return as_dict
 
-    def add_command(self, command: SlashCommand) -> None:
-        if command.cog is MISSING:
-            command.cog = self.cog
-
-        self.subcommands.append(command)
-
     def command(self, cls: Type[T] = SlashCommand, **kwargs) -> Callable[[Callable], SlashCommand]:
         def wrap(func) -> T:
             command = cls(func, parent=self, **kwargs)
-            self.add_command(command)
+            self.subcommands.append(command)
             return command
 
         return wrap