isn't it a 5-star hotel? why does google say it's only 4 stars?

I went there durring the summer, on the wall it had a plaque saying it is 4 stars.

5 stars

Its 5 star rated. Not as much by consumers. But because of consumer reports. When a hotel is considered "5 star" it means that they meet or exceed standards set for that star rating. This includes Amenities like pool, Wi-Fi, Sanitary standards and restaurant standards

It's 5 star!!!!