Exam requires self-imposing a time limit: what should I do when others are likely to use more time?
You’re in an unenviable position and I don’t have clear suggestions how to proceed. But at the very least, it’s worth calling attention to the fact that

your instructor is neglecting their duty to maintain an acceptable level of academic integrity, and

this may rise to the level of being more than just a “feeling” but an actual violation of university policy.


For example, at my university, our guidelines about faculty responsibilities in connection with academic honesty state (emphasis mine):

Academic honesty is an integral part of the University's educational mission. According to the UC Davis Code of Academic Conduct, all members of the academic community are responsible for the academic integrity of the UC Davis campus.
[...]
Faculty are encouraged to promote an atmosphere of honesty in the classroom. For example.
[...]

Use exam and assignment formats that discourage academic misconduct.


Now, to be clear, I’m not suggesting that this is grounds for an official complaint or to ask for the instructor to be punished or anything like that. But the point is, if and when you choose to complain either to the instructor or to other campus authorities (department chair, office of academic integrity etc), citing relevant university guidelines or policies can be a good way of strengthening your case and reminding people that academic honesty is a two-way street in which both students and teachers have responsibilities. When the teachers are neglecting their own responsibiltiies by creating such obvious opportunities for a “thought crime” form of cheating that cannot possibly be detected, they can’t very well expect students to fulfill their side of the bargain.
Good luck! Sorry you have to deal with this nonsense.