So here’s a conundrum. The longevity literature consistently reports that caloric restriction and in particular minimising protein intake, including eg the BCAAs found in protein powders, leads to a longer lifespan. Other things like mTOR that are associated with muscle growth also lead to shorter lifespan.
Basically it seems like you have a choice - live a long life, or get muscular.
There are two subtleties about this that often are not talked about.
1) The caloric restriction -> longevity research shows that it's generally true, but it much more pronounced in small creatures that spend a significant amount of "lifetime energy expenditure" during reproduction (like mice). So while caloric restriction makes a mouse live 30% longer (making up numbers here), the same proportion of caloric restriction may give <1% extra life in a human.
2) There often a quantity vs quality of life trade off too. Let's say reducing mTOR and BCAA takes a few years off of your life but you have much more muscle and with that great posture and movement that doesn't break down your body and you feel great (and if we believe the linked article more sex too). Is that a trade off you're willing to take?
Same argument can be made with HRT for older men (I'm nearing that age). It seems that lots of the scary news related to HRT and anabolics in general is more about looking at the negative effects without accounting for the quality of life improvements that come from just being stronger.
There is no doubt that excessive protein intake is bad.
However, when attempting to reduce your protein intake, great care is required to not reduce it too much, like for everything else that is bad in excess, but which is still necessary for life.
A too low daily protein intake leads to various problems, e.g. a too low albumin level in the blood, which are guaranteed to reduce your lifespan.
Basically it seems like you have a choice - live a long life, or get muscular.