Universities have this issue too, despite many offering students and staff Grammarly (Gen AI) while also trying to ban Gen AI.
Use AI if you want to, but if the person on the other side can tell, and you can't defend the submission as your own, that's a problem.
The actual policy is "don't use AI code generators"; don't try to weasel that into "use it if you want to, but if the person on the other side can tell". That's effectively "it's only cheating if you get caught".
By way of analogy, Open Source projects also typically have policies (whether written or unwritten) that you only submit code you are legally allowed to submit. In theory, you could take a pile of proprietary reverse-engineered code that you have no license to, or a pile of code from another project that you aren't respecting the license of, and submit it anyway, and slap a `Signed-off-by` on it. Nothing will physically stop you, and people might not be able to tell. That doesn't make it OK.
Getting AI to remind you of the libraries API is a fair bit different to having it generate 1000 lines of code you have hardly read before submitting.