This is only a problem if one is writing/thinking on things which have already been written about without creating a new/novel approach in one's writing.
An AI is _not_ going to get awarded a PhD, since by definition, such are earned by extending the boundaries of human knowledge:
I agree, frustration steps in earlier than before because AIs tell you very eagerly that unique thought is already part of its training data. Sometimes I wish one could put an AI on drugs and filter out some hallucinations that'll become main stream next week.
An AI is _not_ going to get awarded a PhD, since by definition, such are earned by extending the boundaries of human knowledge:
https://matt.might.net/articles/phd-school-in-pictures/
So rather than accept that an LLM has been trained on whatever it is you wish to write, write something which it will need to be trained on.