discord.py, the library Killua is currently using, is shutting down
This might not sound like a big thing... but it is. As announced here discord.py will not be maintained or updated starting immediately. Without having support for a lot of discord components yet.
A few weeks ago, discord announced the priviledged message intent. In a nutshell, only bots with a valid usecase for it will be allowed to read messages send by users. This means that they also won't recognise commands because they are also messages.