I think, the API testing feature of Katalon Studio is bogus. Let me show you an example, see
It does not support any binary data in the HTTP response: such as images, pdf, xlsx, zip, tar, mp4, etc. It naively assumes that a HTTP response carries text only (json, xml, text/plain). Terrible, isn’t it.
As far as I see, Katalon is no longer investing their human resources into the API testing features. AI would not cure the poor implementation of the product. I would expect no improvement in future.