Is this pool area reasonable for the master?

There seems to be something wrong with the data you gave. The construction area is 87 square meters, the interior construction area (including balcony) is 65 square meters, and the pool area is 12 square meters. So where is 10 square meter?

If you say the pool area is 12 square meters, the pool ratio is 13.8%. If this figure is placed in a multi-storey house (a building with 3-6 floors), the pool ratio is relatively large, but it is acceptable; If it is placed in a small high-rise residential building (7-9 floors), this value is relatively small and very reasonable, and high-rise residential buildings will not have such a pool ratio.

If calculated according to your interior construction area, the pool ratio is 25.3%, which is relatively large in high-rise residential buildings. Unless there are public areas such as luxury lobby, and the community level is very high, otherwise this value must be problematic.