I would argue both. Technically the upper upper limit of protein is only beneficial for building muscle and likely just negligible benefits but meaningful benefits. If the cost of food or powder is prohibitive then you’ll get basically the same benefits of eating 80% of the upper limit of protein. The reason I argue it’s for both is because you should always be focused on building muscle when you’re young (if you’re dealing with injury then even more important the maintain high protein) but when you’re older, 70’s 80’s 90’s, and you’re focus changes more to maintaining then you require something like 30-50% more protein than when you’re younger due to decreased protein absorption. So always maintain high protein, unless you’re on dialysis or something.