Nah, Ibuprofen definitely affects the kidneys. It's on my mental list of medications never to try again. It always leaves me writhing in pain (thought it was my lower back that was on fire, turns out it was my kidneys).
Have you ever tried dipyrone? Never had issues with kidneys with Ibuprofen, mostly noticed it with the stomach, but dipyrone was very noticeably affecting my kidneys.