Is it risky to take libuprofen for the kidneys?

It depends on many factors, so the answer could be yes or no! Indeed the pre-existing renal function (e.g. renal insufficiency), the use of certain medications (diuretic, pressure medication of the family of ACE inhibitors or ARBs, etc), a state of dehydration (e.g. gastroenteritis). More information should be provided to analyze your case in more detail.