You mean the actual shape of the keycaps?
I think that could perhaps have been covered by a "design patent" once. Those are different from regular "utility patents" ("patents") in that they cover the industrial design of something but not its function.
Design patents expire after a set time period. In the US they last for 15 years, and in the EU it is 25 years except that some countries have a special provision for "spare parts" in which case it is shorter.
The first keyboards with Cherry profile keycaps are certainly older than 25 years old, so any design patent that could have existed on it must have expired.
BTW. In other countries than the US, design patents are not called "patents", so as not to get them confused with actual patents.