@Pooooop Missing out on gelatin is a big one.
Not following restriction on methionine and cysteine makes it even worse.
Better to have both of them to at least mitigate the effects of meth and cysteine.
But there is plenty of gelatin if you choose your cuts well, and it's usually the cheaper cuts of meat that are tougher that contain more gelatin, and the expensive pieces of steak that are devoid of gelatin.
Besides, the older we get, the less protein we need as we aren't anymore into building and growing our steucture, we're more into maintaining and preserving the structure.