Excuse me, TX, who has been to Hong Kong, do I have to tip when staying in a hotel in Hong Kong?

No, actually tipping in Hong Kong is voluntary. If you think the hotel staff has done some extra work for you, you can give it appropriately, but not so much. 20 yuan is enough. Generally, waiters don't have to pay for cleaning rooms because they have their own wages, unlike in other countries. There is one more thing to remind the landlord, don't put money under the pillow of the bed when they are not in the room during the day. Take it all ~