Whey protein powder is not harmful to kidneys in healthy people but can be a concern if you have a preexisting kidney condition. Research has been conducted which found no negative impact on kidney function when on a high protein diet.
Consuming a high-protein meal can raise the pressure inside the kidneys and cause them to filter more blood than usual, however, this does not mean that damage is caused. This is a normal response in kidneys and is not a concern for those with healthy kidneys.
That said, there is evidence that a high-protein diet may be harmful to people with existing kidney disease. If you have an existing kidney condition you should consult with your doctor about the use of whey protein powder.