Of course it is vague, these things always are for both good reasons (it avoids objective limits creating silly situations between what is protected and what can be had through an obvious loophole) and bad (written by lawyers to keep lawyers in business interpreting and arguing about it).
It is fairly explicit in saying that what AI makes for your is not copyrightable, the vague comes from how much work you need to do to make it your output and not the AIs. Too many people seem to equate "asking for something to be made" with "I made this!", as difficult as it will be to make a prescriptive rule about that which pleases enough people (you'll never please everyone) it would appear to be necessary unless we just accept the free-for-all "no one owns anything because it can just be copied, and the copies copied too" option.
