That's all the more reason to demand overtime pay.
It's not like being exempt means an employer is not allowed to offer you overtime pay. They can still do it. You can still demand it.
Cleaning staff are (overwhelmingly) entitled to overtime pay, by law.
Tech workers are more-well-paid than the cleaning staff and generally better situated to negotiate for any given job. But I don't see how that necessarily carries over to increased success in negotiating payment schemes that differ from the legal and industry standard for the position.