What is your definition of bot? Even if you toggle the “I’m a bot option” off you can still access the API using programming interface. Thus you are able to run a bot even if its account has not been defined as a not.

It is probably possible to create a client (like Jerboa or Lemmy-UI) that is able to hide messages from accounts that are defined as a bot.Butt if it hasn’t been defined as a bot messages will still show up, even if they are written by an automated script.