One major test used by the Supreme Court is if the work is an economic competitor to the original. Similarly, infringement depends on the use, not object.

An image coming out of mid journey may or may not be used in an infringing way.

I can download movie stills from Google or midjourney without breaking copyright. If I print and sell posters of them, that is different.

If that were the primary intended use then it wouldn’t be. However the product incidentally has that behavior if you specifically choose to use it in that way, which is not the intended use or the common use.