Chinese New Year is full of celebrations. Many shops will be closed for one or a few days whereas some will not. For the restaurants which are opened during Chinese New Year, some of them may apply additional charge for a period of time.
In traditional Chinese restaurants, the owners would pay extra to their staff who work during the festival (some may not).
The photo above was taken in a Tea Restaurant (Cha Chaan Teng), the bottom says "加一服務費" which means "additional 10% service charge". If the extra charge matters to you, you should check whether they have this notice or go ask the staff.