I booked a hotel in Thailand with CCB's credit card in advance. If I cancel it automatically after 30 days, I haven't arrived at the hotel yet.

Hello, I consulted BOOKING's customer service about your question, and their answers are as follows, for reference only:

After your pre-authorization is automatically cancelled, the hotel will not cancel your room, because the purpose of pre-authorization is more to confirm the validity of your credit card than to withhold the funds in your card.

When you make a reservation, the confirmation letter you receive contains the price of Thai baht, which is the price when you check in. However, if payment is made in a currency other than Thai baht, the confirmed Thai baht price will be paid at the exchange rate of the day.