Generative Expand: how to exclude from prompt

Most results we're getting with an empty prompt are wild: misshapen human monsters being added randomly, text where there's no "need" or precedence etc. Even when we do describe what the space should be filled with, we're missing the option to specifically exclude aspects (i.e. --no people, --no text etc.). It's being ignored and we frequently end up with unusable extended canvases.

How can we improve the results and make sure unwanted elements are not generated?