According to the recent official data, in the spring of 2023, in case of an overstayed visa in the TRNC, you will have to pay a fine. The amount of the fine is 625 Turkish liras (ca 33 USD).
When counting days of overstaying, you need to remember that the validity of the visa starts from the day of arrival.
The exact date of expiration of your visa can be checked in the police department at the place of residence, in the migration department.
The amount of the fine is valid at the time of publication of the post. It might be changed by the decision of the government of the country at any time. The best thing is to check up-to-date information when entering Northern Cyprus.